You will be fine walking the streets anytime of the day/night....there are tourist police everywhere in case you have trouble. Just look for the white uniform! Yeah you will be harassed and it does get annoying. .....Just smile and with patience you will be fine. I found the Egyptians very friendly and funny (even though they try to rip you off any chance given)...just go with flow...one thing to be aware of is when you go to a restaurant. Some of them say there is no menu, thus no prices, and they will hit you with a massive bill for just buying a soft drink. Try to avoid these places and stick with the ones with menus. You will really notice the difference with the Arabs in Egypt compared to the Gulf Arabs....such a difference!! Have a wonderful time!