I am a 27 year old female traveling by myself to Egypt June 2013. I'll be there for 1 week.
There's a great deal of political instability in Egypt, and you'd be wise to keep one eye on media reports about demonstrations and protests during your stay - and avoid them at all costs. Otherwise, especially in the tourist related areas, there's no reason to stay away. Almost all protests occur near to the offices of government officials or political parties, and these buildings are not usually in tourist areas. The exception is Tahrir Square in Cairo. The Antiquities museum stands on one side of the square, so make sure you schedule your visit accordingly. Because Tahrir Square is the epicenter of any protest movement I'd steer clear of it as far as possible.
Also remember, Egypt is a relatively conservative society with what most westerners would consider "old fashioned" ideas about morals for women, so take that into account. Again, that is less pronounced in heavily-trafficked tourist areas.
Have a look at our article about women travelling in Egypt too
Hope that all helps.
Phil from the safety hub. about 6 years ago