Mendoza

It's about an 8-hour bus ride (1.5 hr plane ride?) If you take an overnight bus, you could spend a day there, and take the bus back, but that would be exhausting. Mendoza the town itself is rather dusty and poorly planned, commercial buildings tacked onto a lovely square. But the wineries are beautiful. So I wouldn't allocate too much time for the town itself.

http://www.nytimes.com/2006/12/10/travel/10mendoza.html