hi everyone,
my uncle has lieved in egypt for almost five years and I have visited him there twice, so I have a farely good knowledge of the country (for a tourist)
As mentioned above, the white and the black desert are just fantastic. They are some of the most remarkable pieces of landscape I have seen so far and far less known then the big sigths like the Pyramids and so on.
The "typical" Egyptian stuff is of course also quite remarkable, but be aware, that egypt has far more historical buildings then just the Sphinx, the big Pyramids and the temple of Luxor. No matter where your are, you will always find a worthwile shot.
Espeacially in Cairo, I would mention the many mosques and churches.
This brings me to one very important subject. Be aware, that many people in Egypt are prety religious and even if they are not have a totaly diferent understanding of moral values than "Westeners". Dress accordingly (for men: no trousers, ending above your knees, no bare shoulders. for women: no short trousers (I would recommend skirts), no bare shoulders, no deep decollete, generally not to much skin showing). Many people have problems with getting a photograf taken of them (as Micheal describes in his recent article about marrakech) and one should respect their wishes (I am not totally ok with Micheals "just do it and smile"-attitude in this point).
Also, as all foreigners will be ragarded as rich (remember, alone the flight which takes you to egypt costs more than many egyptians earn in years), don´t be avaricious. Give tips (called bakshish), even for little services (that is totally common in Egypt). But give accordingly to the service. (Most tourist guides have guidelines included)
And as the Islam redommends everybody to support the poor, and you are traveling an islamic country, do so and give spare change to beggars. (or if you don´t want to give money, buy them a bread - works also great for children)
Be patient with children. If they get on your nerves, smile at them. If you can´t stand them anymore, ask an adult for help. NEVER be rude.
Generally you will encounter many things you will not understand and you would change. But remember, you are a guest, so behave like one.
Oh, and I generally only met very courteous people. And I was not harassed more than on my most recent trip to the US for that matter.
EDIT: One more thing: Women should not travel alone, or in an "women only" group. This is one of the great cultural differences. I can´t say that I support this, but everybody who want to travel to egypt as tourists should respect that.
This is worse in rural areas (religious reasons) and in some very touristic areas (because of female tourists in the past, many young egyptians think women traveling alone are "not unwilling" if you know what I mean)