This may be too late to help you but most of the wineries--especially in Bordeaux--will want you to make an appointment. I tried two weeks before I arrived to visit Chateau Haut-Brion and Chateau Margaux and did not give them enough lead time. I am a certified sommelier and STILL could not get in. My hotel had contacts and arranged two excellent tours for me that were excellent. The larger chateaux will have websites and you can decide which ones you want to visit and give them plenty of lead time and you should be able to get in.
I was a little disappointed in the Medoc region from the standpoint of scenery. Bordeaux has a well deserved reputation for making excellent wine but NOT for tourism. They are giving tourism some consideration but it will be awhile before it takes hold.
We stayed in Blaye and crossed the Gironde on the ferry which is rather expensive (€22 OW) and drove around the entire Medoc wine region. They make incredible wine BUT it is NOT the most scenic wine region I have visited. The burgundy region around Beaune is much more beautiful.
However, it is STILL worth a visit and I will go back to spend more time in the town of Bordeaux. over 5 years ago