Recently there have been problems in radar equipment in the Buenos Aires airports, and that has been causing delays in many flights due to the need of complying with safety requirements. If you rely heavily on airplane services, your travel plans could run down the drain.
On the other hand, foreigners are charged higher rates (approximately 80% more than nationals and residents) and that increases the expenses, while bus services are incredibly modern and comfortable, and have still very low rates.
If you wanted to go to Ushuaia on a bus that would mean 36 hours to Río Gallegos, and another eight hours from there to Ushuaia. Obviously, even with a premium bed service (seats that lie back completely flat like a bed) that is too long a trip. And in any case, the premium bed service only goes down as far as Comodoro Rivadavia or Caleta Olivia, some four hours south of Puerto Madryn. From there onwards, you have the option of the classical bed service (something like business class on international flights) or semi-bed. These are very comfortable, but distances are long.
Since there are places worth visiting between Ushuaia and Buenos Aires, let me give you my personal suggestions:
1) Use the plane one way (from Buenos Aires to Ushuaia, and not on the way back, in case you lose international connections). Travel takes about four hours. You can fly either to Ushuaia, to Río Gallegos (from there it is four hours on the bus to the glaciers at El Calafate, or eight hours on the bus to Ushuaia.). There is a very good bus company (TAQSA, or Transportes Automotores Quebek) that features comfortable semi-bed services; they serve no meals on board, but they stop where you can eat at affordable prices. The other company TecnoTrans, by what I have heard from passengers, seems to not be as reliable as TAQSA or MARGA, that belongs to the same owners and uses the same buses.
TAQSA has a direct bus service from Ushuaia to El Calafate (12 hours), although they will probably change buses in Río Gallegos or at their stop for lunch after crossing the Strait of Magellan on the ferry.
2) Of course, you always have the option of stopping at Las Grutas on the way down south, and at Puerto Madryn on the way back, and that you cut your travel in half both ways, enjoying beautiful sceneries.
3) The other option is to fly into Santiago de Chile, fly on LAN Chile to Punta Arenas, taking advantage of their visit Chile special fare, and then cross over to Ushuaia or El Calafate on the bus (there are direct bus services from Punta Arenas to both these cities. Or even traveling on the bus from Punta Arenas to Puerto Natales (four hours' travel), visiting the Torres del Paine National Park, and then continuing by bus from Puerto Natales to El Calafate (some five hours on the bus, with 2 services every day). To check the bus timetables from Puerto Natales to El Calafate, click here:
Travel from Calafate to Puerto Natales costs $12 to $17, depending on the bus company you use. Higher rates may apply in Chile; I am not sure.
From Calafate to Río Gallegos travel takes four hours, and from there to Puerto Madryn another 16 hours. For the first section, consult the same internet site I gave you above, and from Río Gallegos to Puerto Madryn the best service, by far is that of
You will need to stay three to five days at Puerto Madryn, depending on the season of the year. Whales arrive in June and leave in December, while penguins arrive in September and leave in April. The beach season starts in December and ends in March, but you can have nice days for the beach from October to April, depending on weather conditions; during the Summer months, Puerto Madryn can be warmer than Mar del Plata and the beaches are beautiful. Sea lions and sea elephants will be there the wh