I just finished my fourth overnight long distance bus ride in 5 nights. Knowing that I would spend several nights on the bus, I spent some time learning about the bus system. Here's a few tips that I have learned.
1. DO take the bus. Round trip to Iguazu for example was about 400 pesos or $120 US. It saved us a lot of money compared to what airfare would have cost us. And it is cheaper than some hotel stays - albeit not as comfortable. But it includes 2 meals and a couple movies too. Bring your headphones, though they are included sometimes.
2. Get the Cama Suite seats. They are slightly more expensive but well worth it. These are the wider ones that lay all the way down. Make sure they tell you 180 degrees. Other companies call it Cama Total or Tutto Letto. But the titles: Coche Cama, Semi Cama or Cama Ejecutiva are NOT full bed. If you sleep on your side at all, you will appreciate the flat bed. The Cama Suite seats come with pillow and blanket and they have a divider between your seat and the next one in front/behind you to have more privacy and no chance of getting your seat kicked while you are trying to sleep.
3. Ride in the front, on the upper level. We heard this was nice, but then a couple Argentine friends said it wasn't safe, because of the dangerous Argentine roads. Then two other Argentine friends said it was safe. One of our 4 bus rides was in the front and we thoroughly enjoyed it. All of the rides were safe, and the drivers are completely different than taxi drivers here. They drive so smooth sometimes you don't even realize you have stopped for something.
4. Bring a snack if you are a picky eater. The food is ok, but it is typical Argentine food. Argentines eat dinner at 10pm so that is usually when the serve it on the bus. If you need food earlier, bring some. Crackers and coffee and cookies for breakfast. I enjoyed the mate cocido which is yerba mate in tea bags. We were lucky to get medialunas on a couple bus lines. Dinner was usually some kind of warm meat with warm vegetables (eg. boiled carrots) a cold vegetable rice pilaf, crackers, and flan or fruit salad for desert. They provide sodas, water or wine for the meal, and usually provide whiskey or champagne during the movie. Sodas and water are avalable during the whole trip.
5. Do your homework at Retiro bus station if you have questions about what you are getting, especially if you know Spanish. If you don't, Argentine travel agencies can help you. I found a couple online travel agencies that were helpful. See my links below.
www.mawatravel.com - a travel agency found in Alto Palermo shopping mall and Galerias Pacifico. Some bus fares and schedules avaiable on this site.
www.omnilineas.com - a site that gives "omnibus", or long distance bus, travel info, schedules, fares, etc.
www.tebasa.com.ar - the Buenos Aires Retiro bus station website. It does not offer schedules or prices, but you can enter your destination, and it will list contact info of the companies that go to that particular destination. Then you can call them or search for their website.
Please add your own tips and experiences below on this topic. I am going to add my reviews of the three lines I took in a separate post. I think many readers will find this info useful since TA does not have a way to post reviews on specific bus lines in Argentina.