Pros: it will be out of season, so getting a reservation will be easier. Otherwise I would advise booking months in advance for the established wineries.
Cons: temps will be in the 50s.
Not sure how much time you have, but would spend 3-4 days visiting the different subregions of Bordeaux:
1. Left Bank Part I (Medoc): visit a couple of wineries (eg, Margaux, Pauillac, St Julien, Pessac). The Medoc alone has a ton of really good wines (particularly red varietals) from which to choose.
2. Left Bank Part II (Graves): visit a couple of wineries (eg, Haut-Brion, Pape Clement). FYI, Haut-Brion has several chateaus on the left bank, so choose whichever one has wines that fit your palate.
3. Right Bank (St. Emilion): visit one or two wine houses (eg, Cantenac). I highly recommend spending a day visiting the town of St. Emilion. Well worth it. Bring good walking shoes as the streets are cobblestoned.
4. Right Bank (Pomerol): visit one or two wine houses (eg, Petrus), most of which are relatively modest.
Not sure where you are staying. Let me know should you need any other S&Rs.
Class of '91 (MEEN)