In reply to ablackett:
If you can plan a route that takes in more than 3 or 4 good climbs without covering A LOT of ground then you are dong well, for instance, Croix De Fer, Telegraph, Galibier is a good 90 mile ride from Allemont and back, circuit of the Izoard from Briancon is around 40 miles from memory, generally you will end up doing out and back a lot if you are col bagging, there is of course a hell of a lot of smaller cols around that you can link together but the classics are a challenge to do circular.
Where are you headed too specifically ?
And as above, climb by bike is your bible for cols, otherwise plan your own using ridewithgps.com and download the GPX files to the Garmin.
Post edited at 19:41