In reply to Owen W-G:
Are you planning a complete walk of Dovedale out and back? If not, then the south end (Ilam) car park is nearest the stepping stones, whereas the north end hamlet of Milldale is best for ice cream, butties etc.
If you're staying near Bakewell, take her to look at the big trout in the river by the footbridge. Also loads of ducks and geese to feed.
The various mentioned mines are worth a visit and you get a nice ride in a little boat in Speedwell Cavern.
The Pavilion Gardens in Buxton have a good kiddies playground and a little train to ride on.