In addition to the great pyramids, make some time for the step pyramid and the surrounding area. You can go inside of these and they's absolutely amazing artwork inside. Unfortunately, the great pyramid has very little of interest inside. Also Luxor down in the south of Egypt would be worth a stop.

A few other ideas. Mount Sinai. Petra in Jordan. Israel for just about everything of historical interest if you're into that sort of thing.

If you haven't been to a muslim country before it can be a bit of a culture shock. Get familiar with traditions, basic customs, and a few polite phrases. Not to scare you away (it's definitely worth the trip) but make sure you check travel advisories before you go. Be wary of scams and potential threats.