Castleton is a very popular area for all sorts of outdoor activities, Mam Tor and the Blue John caves, can get very busy during Bank Holidays though - I think the site near there is called Losehill, although I've never stayed there.
nearby Hathersage also "boasts" the grave of Little John of Robin Hood fame, although wander through the graveyard to find my favourite, Fanny Rust! Seriously!
there is also the Ladybower reservour which I think you can walk/cycle round, and there are plenty of pubs in that area for stopping at.
a bit further out Matlock Bath is a plesant enough place for a visit, think you can take a cable car up High Tor or even climb it!
nice area, and no I dont work for the tourist board... M (",)