I don't know a lot, have been to Europe plenty but not much as a rider.

That said, did a 2 week trip this year, including L'Alpe, and it rocked. We stayed 5 days in Alpe D'Huez, and from there we rode Telepgraphe, Galibier, and of course the Alpe. I assume from your post that you like to climb, and there are a load of really beautiful and challenging rides in the Isere valley and the Hautes Alpes generally, including Izoarde, Agnel, Lautaret. You are also not far from iconic TdF stage locations like Gap and Grenoble, so you could certainly achieve your '100-140km for 6-7 days' goal just by doing that.

We also spent a week in the Luberon, and it was great. About a 4-5 hour drive from Isere, and some beautiful hilltops all around (like Gault), but the only really big iconic climb is Mont Ventoux - an awesome ride in itself, and you can do it via any of 3 different routes, but still just a single mountain.

Wherever you go, hope you have a blast. What a great adventure!