Dahab is a good shout actually TooTall, I went there a few years ago when there was barely anything there! Great diving, cheap as chips and not too many idiots or for that matter Egypian men either harrassing you or asking if you will sell your girlfriend / wife (was amusing at first until they started trying to touch her hair)!
Diving is probably the best I've seen especially "The Blue Hole", "The Caves" (saw turtles here, which was awesome) and anywhere along Hilton Beach is easy and a quiet place to learn.
Sharm is good if you want something a bit livelier with bars and clubs, but I personally found it a bit irritating after a couple of days. Head for Pinkies Drop (really mental if you aren't expecting it as you walk out across a beautiful coral reef to suddenly tip over the edge of a 300 metre drop into blackness below - scary stuff) and Jolanda (again I saw turtles and white-tipped reef sharks) but this gets mega busy!
Have a great time whatever you choose but I would definitely recommend diving in Egypt as one of those once in a lifetime experiences! You never know you might want to take it up properly, I did!
Good Luck