Are you all booked up yet? It depends on your partner, but Sharm is not ideal for a non diving partner. All the diving is boat diving and you spend pretty much all day on the boat. The town is pretty good for evenings, though. It is much like a European resort.
It is only a 1 hour taxi ride up the coast to Dahab. Here all the diving is shore based so you can do a dive in the morning then have a long lunch in town or on the beach before an afternoon dive. The town is far less cosmopolitan (putting it mildly), it depends what you like.
Sharm is far more expensive than Dahab, but still cheap by European standards.
The diving is pretty stunning in both locations and you will certainly enjoy either place.
What type of accomodtion are you looking for, what type of diving do you want to do?