It depends on your level of fitness. I can recommend some walks in France, but in the mountains they often require good fitness as you may have to walk 1000 m elevation gain every day. I know most people do Tour du Mont Blanc, but it's actually not the best scenery. I think Tour de l'Oisan would be better, but it's also for fit people. Also called as GR 54, it's a total of 12.5 km elevation gain in 12-14 days. Only english info I could find is this :
http://www.cicerone.co.uk/product/detai ... fqqGZefqao . The Ecrins massif where Oisan is situated is better for a 2 week walk than say the Mont Blanc or Vanoise because it benefits from a lot more sunshine each year (it rains/snows only about 60-90 days a year, while up North it's twice that), but it's also famed as one of the hardest GRs in Europe.
If you tell us your level of fitness we can advise in more details, also tell us if you'd rather do a coastal walk or mountains.