Great tips all around, guys!
I travelled to Egypt in December, right after 9/11. We had arranged the trip way before 9/11, and considered cancelling after. Then we got mad and decided that we were not going to let it ruin our trip.
Anyway, we were treated very well. Several Egyptians, upon learning we were from the USA, actually approached us and told us they were very sorry for what happened.
Security was very tight and our group of five Americans were required to travel with an armed guard most of the time. We felt safe and secure, every step of the way.
If you are single and travelling to any touristy type areas, get yourself a cheap "wedding band". This even helps in certain situation back here in the states. Also, zip-off type pants, loose-fitting, of course, are invaluable for travelling from one area to the next in comfort while still being able to be "up to code" in more "formal" situations.
I have been fortunate enough to be able to travel to many places around the world. I have found that generally, if I am polite and respectful of the people I come into contact with, most interactions are very positive and fun. It's important to learn the cultures of the places you intend to visit, respect those cultures and, above all, have a good sense of humor!