Arriving Argentina 1 week before Easter. After 2/3 days in Buenos Aires, we wish to then travel to Mendoza by overnight bus, stay 3 days and then move onto Cordoba, eventually heading to Salta. Question: we are worried about obtaining bus seats and accommodation over Easter Holidays and would like to book the buses before we arrive in Argentina. For the accom. we can book online but is it possible and reliable to do this for the bus travel and does anyone know which bus sites we can access to do this? Also, what are the actual days people have off for Easter? Thank you for any assistance.

A couple of sites which may help:

http://www.andesmar.com/shop/default.asp?lang=en
http://www.omnilineas.com/
Not sure whether you can book on-line with a foreign credit card but it seems at though its may be possible by phone. We used Andesmar extensively in Argentina and found them to be very good. Make sure you book full Cama for long trips

You can book Andesmar online.
Most people will start the long weekend with a half day Thursday, so buses get busy on Thursday afternoon/evening and Friday for those who had to work Thursday. More complicated is Sunday when nearly everyone is heading back. A few will travel earlier or back later, but that is the general outline of movement.
Definitely book your lodging.

Thanks so much for your replies, most helpful.

I booked most of my bus tickets online through Andesmar about a month in advance... I wanted to make sure I got the 1st class cama seats. It was very easy, and yes, they did accept foreign credit cards.

Not sure if you can book online but we recently took the overnight trips to Mendoza and back from B A with Chevallier and Cata Internacional. Make sure to book the cama suites. They were excellent compared to Canadian Greyhound buses. Bring earplugs just in case you end up with a snorer near you like we did.

MsLizzy - Excellent advice about the ear plugs! Essential equipment for overnight bus or air travel.

Just want to add that we were able to book our bus tickets for over the Easter break online at: http://www.andesmar.com/shop/default.asp?lang=en
although we were unable to travel exactly and to where we wished as this busline was full. However, we came up with a good compromise and it's a relief to know we have the Easter planning out of the way and after that, buses and accomm. should be no problem.