Longwoods may be able to organise something for you if you give them a ring, otherwise you might be better off going in to a high street travel agent and seeing if they can tailor make something for you. Taba, Marsa Alam and Hurgharda have airports if you want the Red Sea, but dont want Sharm, I'm sure you could get internal flights with someone like Egyptair.

Infact thinking about it I think Thomson/Portland do two centre holidays with a nile cruise followed by a week in El Gouna/Taba Heights etc, so it might be worth getting their brochure.