You'll be spoilt for choice up there but this link should give you some idea's. Don't forget places like Bakewell as well which can be good fun on market day which if I remember correctly is Monday's. Arbor Low is a truely magical place and out of season you can sometimes get it to yourself.

nealy forgot that anywhere along the River Dove will give you beautiful river / waterfall shots.

Have fun and I'm looking forward to seeing what you capture.