In Mendoza you'll want someone driving you to the wineries, in part because it's very easy to lose your way and partly because you'll consume enough wine that you won't want to drive. I think we paid about $80 (USD) a day for a driver which we found extremely reasonable. Some people do charge more as I found out. When it comes to transportation I'd book ahead just to be safe. The Vines of Mendoza website has some guys they could recommend or I'd be happy to give you the contact info of the guy we hired last year.

If you're staying anywhere near the center of Mendoza you'll be able to walk or get a taxi to take you anywhere you want to go. We never paid more than about $10 for a cab trip except for from the airport and that still was only $20.

Our winery tours were generally about 45 minutes to an hour long (not including tastings) and they take you throughout the entire operation. Since many of the wineries are small you'll sometimes get the owner or someone in the family doing the tour, but they tell you all about the history and will pretty much explain anything/everything you want to know.

The tastings were more intimate than anything in California from my brief experiences there. Many of the wineries still don't charge for tastings but the ones that do are very cheap (their websites are good about giving you an idea of the cost and what you get to try). They'll walk you through what you're tasting and the tasting sizes were close to a full glass of each at many places. Overall the tastings are a wonderful experience.

Hope this helps, others on the board can share a lot more than I can and talk about BA since we didn't make it there.