Can anyone tell me about traveling by land from Buenos Aires to Asuncion, Paraguay?

I came the opposite direction and believe me when i tell you how lucky you are youre not on here asking to get to Asuncion from La Paz! Your route is not only very doable but is also a nice trip i hear. As the previous poster said, many nice bus companies, for long trips the Semi or Full Camo classes are a must ask in the office before booking your tickets. The Argentinean bus service we preferred is called Andesmar and was excellent all round. You can use this service right up to the border of Argentina and then you'll have to change company. Your Route... Buenos Aires > Puerto Iguazu(Stop here if you have time, stunning.15-17 hours. Get nice bus for a little extra cash) > Ciudad Del Este(We crossed Paraguayan border at Foz do Iguacu, Brazil but im sure its the same) > Asuncion(Change bus here for a standard coach as youre only 5-7 hours away which is a piece of cake). As far as im aware thats a good doable route however if youre going straight there without any intention of stopping at Iguassu this may not be the best route. If so you should research crossing the paraguayan border from the south instead which may or may not be faster. As for prices im afraid i cant help you there as ive long since forgotten but a quick flick through the Footprint guide to South America(Not Lonely Planet which is wildly out of date price wise at this stage) will fill in the blanks for you. Hope that helps. Ask anything else if needs be.