Hey man...
I've been lucky to spend some time down there. There's a couple of good spots - where exactly in the city will you be staying ? From what I can recall I still have some business cards to point you in the right direction - but most of them are in the more residential parts of the city.
That said - even if you aren't a wine junky, you must check out Concha y Toro and Santa Rita. They're about 40mins outside of the city, and worth the trip. If possible, book a lunch @ Santa Rita...but be prepped for a 3hr lunch in a beautiful barn. IIRC they're a larger-than-life painting of the Crucifixion, with JC smashing grapes..
Also get a car - the driving is excellent:
