The following is the itinerary that we sent our family with. They reported that it worked out quite well.
Dec 24th --
Morning: Arrive in BA
Afternoon: Check-In to Hotel Ask your hotel to book a Tango show for 26th night. If the prices are too high, ask them to book "Madero Tango", it's 110 pesos/person for the show (no dinner) and includes transportation. The San Telmo Tango show is the most famous. Book Classic City Tour for 26th morning -- ask for an all-English bus. Research tours in the Tigre Delta for tomorrow. There will be boat tours, or kayaking, etc. The tour we took was 85 pesos/person and started with a Bus in BA, that took us to a touristy train, then back to a bus, then a boat tour on the delta. Read tomorrow's description to see the cheaper way to do it. Ask your hotel to find out confirm that the amusement park in Tigre is open tomorrow (it says its open Fr/Sa/Su and holidays. Dec25th should be a holiday -- the name of the park is Parque De La Costa)
Evening: Explore area by walking. Visit San Martin Plaza, it's just outside your hotel. Then walk down Florida Avenue (Avenida Florida). It's a pedestrian street that has many shops, and after 6pm, there should be street vendors sitting in a row selling handicrafts. At the end of Florida Ave, you will arrive at Plaza de Mayo. While you will see this on the Classic City Tour on the 26th, feel free to look around. The street called "9 de Julio" is the largest street in the country and worth seeing. Get the hot chocolate at a restaurant called "Libertad Plaza" -- see details below.
Night: Probably fireworks at midnight since Christmas Eve is celebrated in Buenos Aires more than Christmas day. During daytime 12/24 and 12/25, fewer restaurants open and fewer taxi's available but evening should be open again. Your better chances are in Palermo and Recoleta neighborhoods. You might need to book a restaurant in advance so ask the hotel about this when you arrive. Subway is still running. Malls are closed.
Dec 25th --
Morning: From the train station at Retiro (on the other side of San Martin Plaza) take the commuter train (2 peso/person, ~30min) to the Tigre Delta. Stop at Tigre (last stop). Once you're there, find the boat tour companies and take a 90min boat ride around the various islands. The station is 200 yards from the boat docks. But find out the timing for the last train. There should be one train every 30min. There might be more extensive boat tours that might be more interesting. You can go kayaking in the water as well.
Afternoon: After the boat tour, you can visit the amusement park and casino. They are both walking distance (< 1/2 mile) from the boat docks. Return to BA. Return trip on the train is from Tigre station to Retiro station (last stop).
Evening: Explore the shopping. It's possible that because it's a holiday the handicraft fair is open at the Plaza Alvear (very close to the Cemetery). Usually it's open Sat/Sun. If it's open, you will find hundreds of handicraft stalls, many many more than Florida Av. It should be open until the sun goes down. The fair is close to the Hard Rock Cafe, in case anybody wants Nachos.
Dec 26th --
Morning: Picked up by a Bus for the Classic City Tour. You will most likely stop at Plaza de Mayo and the Caminita area of town. Caminita is not in a great part of town so take advantage of being taken down there. Caminita is the best place to buy soccer or tango related souvenirs, also a small handicrafts fair there. You will return to your hotel around noon.
Afternoon: I'm not sure what you will be interested in, but since you have all day, think about the Rose Garden & Japanese Garden (open until 5pm), Museum of Fine Arts (Museo Bella Artes) open unti 8:30pm, the Museo Arte Decrotiva (open until 7 pm), or the Cemetery. If you taxi to the Cemetery, you can walk to all of these. Consult the map to gauge how much how much walking you'll be doing -- it's quite a bit.
Evening: Tango show pickup time is ~9pm. Many people dress up for the show.
Dec 27th --
Morning: Fly to Iguazu and check-in to your hotel quickly. Leave for the park as soon as possible.
Afternoon: Our 'tour' took us to the "Devil's Throat" falls. It's the biggest and the last stop on the train. Then take the train one stop back, to start the 'upper trail'. Once you come back down, try to find the fast food place(Dos Hermanos). If you plan on buying food, buy it now as they run out of food. then you can take the 'lower trail'. The boat ride is at the bottom of the 'lower trail'. I believe tickets can be purchased towards the bottom of the lower trail or at the visitor's center as you enter the park. After the boat ride, you have seen the best sights in the park. when you reach the top of the lower trail you will be back to the fast food place. If you walk towards the visitor's station you will come upon a sit down restaurant. If you decide to go to the Brazilian side of the falls, talk to the visitor's center before you leave. If you make it back to the hotel while it's still hot out, you can swim in the pool.
Evening: We ate at a restaurant called 'Colors' both nights, it was pretty nice and very busy after 9pm.
Dec 28th --
Morning: You could go to the Brazilian part of the falls, or you can go for a walk in the city of Iguazu. There isn't too much to see, but it's a 20 minute walk down to the Iguazu River. There might be people there offering you scenic boat rides, but don't expect anything spectacular.
Afternoon: Fly to Trelew, Drive to hotel in Puerto Madryn. Ensure you have reservations to see the Penguins tomorrow. Try to request an all-English bus.
Evening: You can walk on the beach, along Avenida Roca, or try to find shopping on the street called "28 de Julio". We ate at restaurants called "Las Dunas" and "Lizard Cafe". There wasn't anything special about these restaurants, I imagine they're all similar -- just consult their menu to make sure they make vegetarian food.
Dec 29th --
Morning: You'll be picked up from your hotel to visit the Penguins. After a 90min drive you will arrive at the penguin colony, "Punto Tumbo". There you will spend 60-90min with the penguins. It will be very windy. After that, the bus will take you to the town of "Gaiman". It was original a Welsh town (Irish descent) and they will try to take you to a Welsh Tea House. For 40 pesos/person you will be served tea and biscuits. If you choose to explore the town, it's likely you will find everything closed as the tour comes in during "siesta". You can eat your own lunch in a plaza or playground.
Afternoon: You will then be taken to Trelew and park outside a Paleontological museum. It's a nice museum with many giant dinosaur skeletons -- however, there are only a few descriptions in English. Entrance is 23 pesos/person.
Evening: Decide whether you'd like to do another tour tomorrow or just relax and visit a museum. Make sure the tour doesn't try to make you see whales (they're gone) or make you stop at a restaurant for mandatory meal. The only animals left to see are Seals, there may be a short tour you can take just to see the seals. If you like it, you can book that for 30th morning.
Dec 30th --
Afternoon: A 15 peso taxi will get you to the Eco-centro museum. It's a very nice museum, with all information in English (and Spanish) and lots to learn about the marine life of Puerto Madryn. Entrance is 25 pesos/person. Museo Oceanographico is also supposed to be very good, but we did not get a chance to visit it.
Evening: Fly to Buenos Aires. Ask the hotel to find out where people might be celebrating new year's eve. If nothing appealing is going on, try to book a tango lesson for tomorrow.
Dec 31st --
Morning/Afternoon: Try to finish the sights/activities you did not finish on the 26th. You can also choose to visit the Ecological Reserve. Lots of walking and bird watching. From there you can visit Puerto Madero -- it's the most modern part of Buenos Aires and has the best restaurants (or so we heard, we didn't get a chance to visit).
Evening: Celebrate new year's eve or Tango lesson. Looks like most of the city shuts down early on NYE (around 9pm). Most young people either go to Rio, Brazil or Punta del Este in Uruguay but accomodations and booking may be difficult and expensive this late. Restaurants may be closed, Recoleta and Palermo neighborhoods will be best options to find open restaurants and close enough to not have to find a taxi (sparse on New Years Eve and Christmas Eve). Might find some celebrations around town through your hotel or on newyearseve.com website.
Jan 1st --
Morning: Finish anything you haven't seen yet or explore shops on Av. Sante Fe.
Evening: Return to Int'l Airport. It's at least a 45min drive if you leave around 8pm.
Restaurants -- Many did not mind that we brought our own water bottles. Expect a table service fee for the bread rolls brought to your table before the meal.
Mumbai - Indian (recommended by Anita)
Tandoor - Indian
Namashkar - Indian
Libertad Plaza - 1200 Santa Fe -- Excellent Hot Chocolate, order the "Chocolate Especial" (very close to the Marriott)
Solo Empanadas - a chain of cheap empanadas, they will deliver if you order a dozen. Each is about the size of a samosa - they have 4 vegetarian flavors and 3 dessert flavors.
Freddo Ice Cream - Order The "Dulce De Leche Con Brownie" - bigger sizes of cups/cones include 2 scoops of ice cream.
Hard Rock Cafe - Nachos
McDonalds and Burger King are everywhere
Subway (saw one near the big mall in BA called Galleria Pacifico) but did not try it out.
Evening: Tango lesson. Explore Puerto Madero - It's on the way back from the Ecological Reserve. We're not sure what there is to do in Puerto Madero because we didn't have time to explore it. It might be worth seeing, it's the newest and richest part of the city. We do know that the restaurants in this part of town are supposed to be the best.