Route des Grandes Alpes is a set route that you can ride at your own leisure, taking in the most impressive French Alpine climbs possible. You can spin off into Italy over Galibier/Lautaret. This route is ridden by many supported and commercial tour companies.
Here is some info on Italian Alp
routes. Try and fit Stelvio Pass into the route, even if you have to backtrack.
Ive ridden in the French Alpes and some of the minor routes and non-through roads are better cycling then the big, famous, but busy passes. You can stop off and ride a few days routes around Grenoble.
The North Sea cycle route has its charms but there is no comparison if you want to do serious climbing. The Raid Pyrenee is another famous climbing route but riders often look at the clock and mile-ometer too much to beat the 100hr "deadline"
High mountain roads are passable between May and October. Summer holidays are v busy, expensive and too hot. The best riding is to be had in late May/June and Sept.
Last edited by MichaelW; 02-16-12 at 11:12 AM.