Taking a Felucca down the Nile is something you must do when visiting Egypt. Feluccas are sail boats that have been used on the Nile since antiquity.
You can take short sunset sails in Cairo and Alexandria or you can opt for longer cruises which usually depart from Aswan. A Felucca is not quite as comfortable as a luxury cruise ship but nothing can beat sailing in a quiet rig that was designed thousands of years ago.
We booked a 3 hour trip on one whilst we were in Aswan, but spent closer to 4 hours on board. Some people shared their boat with others, but we got one all to ourselves.
This was one of the highlights of the trip for me.