In reply to hpil:
Écrins/ Brainçon is a good shout, lots of camping options.
for activities, it has the best white water in France, so a great place for rafting, there are 26 via ferrata and 1 via corda, (I have made a free app guidebook for via ferrata, search googleplay or app store for via ferrata Ecrins and Braincon it has all the details, map and a like to google map to get you to the parking etc.).
Rock climbing there is loads to go at ( I moved here for the climbing) over 80 crags, 6 different rock types, all grades, plus lots of multi pitch routes that are great with kids.
For walking non-glaciated, there is lots round Brainçon and the Cerces, and a short drive takes you to the Queyras park, which is amazing for walking all have huts for over night walks. I am making an online walking guide but it wont be ready till the summer.
lots of mountain biking as well, some lift feed stuff and lots of peddle power stuff, and Puy st vincent has a summer luges, and I think some of the other resorts have them as well.
For the driving it is passable to base your self in one part of this region and get lots done, but if you are willing to drive up to an hour it open up 3 mountain ranges with loads to do.
I live here and work as an climbing instructor, International mountain leader and kayak guide also writing online guidebooks, I am happy to help if you would like more info or advice.
Cheers Rob