We went to Mendoza this past weekend, and it was awesome. One of the best parts of the trip was the bus ride, believe it or not. This post by someone else does a better job of describing it than I could. The differences between what they described and what we experienced were that we went both from Santiago to Mendoza and back rather than just one way, and that our time at the border crossing from Argentina to Chile was more like 3 hours than 2. Oh well!