Lac D'estaing, Estaing

This is gorgeous, picturesque setting, with a great restaurant at the other end of the lake. There's only one road into the valley, making it seem very isolated, but at the other end of the road is a good size town. Although it's a bit of a tourist trap (yes, they bus in tourists to see the lake) at night it's quiet and pitchy black, so take a good torch! A nice lady at the site even brought morning patisserie for us if asked.
There are places for riding on the spot, a reasonable bar/snack place and just some of the best views in the Pyrenees.
I can recommend visitors to go and see the Donjon des Aigles, which is a bit like the Hawk Conservancy in Wiltshire, only waaaay more exciting - they have hawks, eagles, vultures and other birds of prey wheeling round in a really spectacular display!
You can easily reach Northern Spain from here, which is worth a look, because the scenery looks completely different on the other side of the mountains.