Thank you sf7307 and frogoutofwater.

I had thought that the heat would possiblily be an issue. I haven't travelled in hot climates. I will check shoulder season prices and maybe I'll travel a little later than I had orginally planned.

dutyfree: We spent 4 nights in Luxor and one night in Aswan. We arrived in Luxor around 4 pm and had time to go to one of the temples and then have dinner. On our departure day, we left early for the drive to Aswan and did some sightseeing along the way, arriving in Aswan in late afternoon, with a little time to walk along the Corniche but not to do much sightseeing. We then had a very long day in Aswan because our flight didn't depart until 11 pm. So, effectively we had 3 full sightseeing days and one quarter-day in Luxor, one very long day in Aswan, and a half day spent on sights between the two. That worked for us and we weighted the trip more to Luxor because we had a free, very nice hotel at our disposal. A little more time (maybe half a day or two) would have been nice in Aswan.

I think that the amount of time spent in the two cities might also depend on the time of year. It was so hot when we were there that we didn't feel like having a jam-packed sightseeing day. If you went to Egypt when it was cooler, you could probably fit a little more into each day and therefore be able to cover Luxor, Aswan and Abu Simbel in the amount of time we spent just in Luxor and Aswan.

It is nice to spend more than one night in a place; I usually to spend at least three nights whenever possible.