Presumptious again but I only have experience of Mrs G and family...

Castleton, in my experience as above, would be more a 'ladies' place in that there are more gift shops and more to do and see by way of attractions. Personaly I prefer going up the high tops where there is bugger all to do but far more to see;-) Before you ladies who do go up the high tops start having a go at me remember I did say it is only in my experience!

There is more by way of accomodation in Castleton as well. Are they staying over? Are they doing any walking? If so what level? Castleton does seem to provide something for all but as I said it is busy. Rightly so I guess because it does have so much! As you said it is a bit 'twee' though. It all depends what your friend is looking for.

How about Hope if that is the area you are looking at? Walking distance from Castleton but more a 'working' village? Or, if accomodation is not as important, as I said before - Edale.

Cheers

DtG