My daughter and I are going to arrive in Cairo on a Sunday and fly to Luxor on the next Wednesday. Then we fly out of Luxor on the following Sunday. I saw there are two day tours to Aswan, which we are thinking about. Any suggestions?

Also, our flight leaves out of Luxor at 4:50am. A hotel would not be worth the money because we would have to leave at around 2am. Can we just spend the night at the airport?

I'm sure you're aware of how little time you have, especially for the enormous amount there is to see in Luxor. With just 3 full days there I wouldn't reduce it to 2 by going to Aswan. I loved Aswan but spent a week there. A day trip would mean just hours that could be better spent in Luxor without the relatively wasted time for travel to & from Luxor. I just don't think it makes any sense at all. So my suggestion is to concentrate on the sites in Luxor and maybe get a feel for the very interesting town as well.

I don't know if you can, but wouldn't want to spend hours at the Luxor airport. You'd be better off making arrangements with your hotel to spend the evening there, even if you don't have a room. Have them hold your luggage, have a leisurely dinner then relax in the garden or lobby. You might even ask them for a special deal to have a room.

Have a look, if you like, at my report and especially at what's in Luxor where I spent over a week and still didn't touch many of the West Bank sites:
https://www.travelgumbo.com/blog/portmoresby-in-egypt

Ditto, 3 days is the least you need in Luxor if you're interested in Egyptology. If you're not interested in Egyptology you'd better spend those 3 days on a Red Sea beach.

Hotels are very cheap in Egypt, so spending an extra night in a hotel(even if you don't sleep and leave at 2am) is not wasting much money.