We just returned from 12 days in southwestern France. I did a lot of homework and made appointments for private tours and tastings at the top chateaux. However, we also went on the Bordeaux Office du Tourisme tours. They are excellent. The guides are bilingual (English/French) and highly informed. Go to the website and book your tours in advance. They are very popular -- completely booked even in November. The price is very reasonable for what you get -- an English-speaking, well-informed guide, someone to drive you around, and visits/tastings at either two chateaux or one chateau plus a town tour (St. Emilion, for example).