It’s touristy and overdone, but you have to have sailed on the Nile once in your life, it’s one of the most famous rivers in the world. Especially because the Nile was one of the most important waterways for the ancient Egyptians, and the view of the many monuments and archaeological finds from the water is quite special.
These days there are so many options for cruises leaving Luxor. You can spend an hour on the water, but you can also spend several days cruising to Aswan (and back, if you like). Many tourists book their cruise before their trip, but you can also book it at many hotels and shops in the city.
Make sure you give yourself time to see both the eastern and western banks of Luxor. You can easily spend a whole day here, but if you really want to see it all, you’ll want to spend longer.