We were supposed to go on a group tour, which became a private tour, as nobody else signed up for May. The itinerary is as follows:
2 nights in Cairo at the Mena House - touring the pyramids, Solar Boat , Saqqara, and
Memphis - fly to Luxor late in day 3
4 nights in Luxor at the Winter Palace - A day in Karnak, with visits to the Luxor Museum
and temple, a day at the Valley of the Kings and Deir el Medina, a day seeing the
Ramesseum, Medinet Habu, and the Valley of the Queens, with another day at
leisure or a day trip to Abydos and Dendara
3 nights Nile Cruise on the King of Thebes -with the usual sightseeing tours
2 nights in Aswan at the Movenpick Resort - felucca ride, Elephanta Island, Abu Simbal,
Nubia Museum and Temple of Isis at Philae
2 nights in Cairo - Nile Hilton- seeing the Egyptian Museum, Khan el Khalili bazaar, and
and the old Cairo sites.
Has anybody been to Abydos and Dendara? Any thoughts on the itinerary?

Your itinerary sounds fine but I do have a few questions. Where is your Nile Cruise taking you? The usual Nile Cruise stops (when heading North) take you to Luxor Museum, Karnak, Valley of the Kings & Queens Deir el Medina, etc. You will be spending 4 nights in Luxor at the Winter Palace seeing these things. Or is your Cruise taking you in the other direction, South? Will the cruise take you to Abu Simbel? Abu Simbel is a must but you don't say if you are headed there. If your cruise takes you to Kom Ombo, Esna, Edfu, and several other places then you're fine but check out the Cruise itinerary so you don't revisit what you've already seen.

Our cruise took us to Abydos and Dendara and they both were wonderful. Abydos was one of my favorite places. I had really wanted to visit the Temple of Abydos to see the List of Kings and it is fabulous! The Nile is magnificent in these areas. Much slower and more rural than in the Luxor area, with very few boats cruising the waters there. You pass through very small fishing villages and sleepy little hamlets.

oops. sorry I see you are going to Abu Simbel. Wonderful!

The cruise goes to Edfu and Kom Ombo and ends in Aswan. There is no exploration of Luxor while on the ship, hence the 4 night stay in the hotel there. We are flying roundtrip from Aswan to see Abu Simbal. The tour company representative said that allows more time at Abu Simbal then doing it as a stopover on the way to or from Cairo. I had questioned it, because it meant an extra visit to the airport, as we fly back to Cairo the next day, but she said the extra time in Abu Simbal was worth it.
We have taken river boat cruises around Holland and Belgium, as well as in Russia. I enjoyed looking at the scenery, but picked the shorter cruise on this trip because there was so much to see in the Luxor area. I hope this was the right decision.
I guess we will do the option to Abydos and Dendara - it does not look like a long ride from Luxor. Thanks

Honestly, I think you're spending too much time in Luxor and Aswan - Karnak and Luxor temples, Valley of the Kings, Valley of the Queens, Luxor Museum can all be seen easily in two days, and you'll still have your afternoons at the pool.

In Aswan, there really are no sights other than Philae Temple and the High Dam (10 minutes - there's really nothing to see).

I think you'll have a lot of free time with this itinerary, which may be fine, especially if it's good weather. We spent the afternoons at the pool in both Aswan and Luxor and it was lovely (but we were there in August, when it was deadly hot).

Well, it's certainly a leisurely tour and for May when it's hot, can work. I feel though that 4/days in Luxor and then 2/days at Aswan and then 3/days cruise might be a bit much.

You can visit Valley of Kings and Queens one day, usually done early early morning when it's somewhat cooler and late-afternoon the Luxor and Karnak temples. ; relax at pool in afternoon. I would definitely use a day to visit Abydos and Dendera.

While there are a few sights in Aswan, besides the High Dam and Philae Temple, you don't need 2/days. These can both be done in the morning. The Nubia Museum should be visited during the cool part of the day, late afternoon when it reopen, and the souk (market) here isn't near as crowded as in Cairo.

If concluding cruise in Aswan, you might require an overnight and then next morning fly to Abu Simbel, tour the sight (2/hrs max) and fly back via Aswan to Cairo, if it's not a direct flight ABU/CAI.

We did a similar trip, but in less total days in Egypt.
Day 1 - Arv CAI evening - o/n
Day 2 - CAI, pyramids, sphinx, Memphis, Saqqara, opera at the pyramids - o/n
Day 3 - CAI, museum and bazaar - o/n
Day 4 - Fly to Abu Simbel (2/hrs); fly back to Aswan to board boat; afternoon sightseeing - on boat
Day 5 - ASW - Temple of Philae, High Dam - cruise o/n boat
Day 6 - Cruise - Kom Ombo - cruise o/n boat
Day 7 - Cruise - Edfu and Esna, arv Luxor - o/n cruise boat
Day 8 - LUX - Valley of Kings/Queens; evening Light & Sound at Karnak - o/n cruise boat
Day 9 - LUX - morning visit Luxor and Karnak temples; afternoon at leisure; late afternoon fly to CAI - o/n
Day 10 - CAI - sightseeing on our own, back to bazaar and museum - o/n
Day 11 - Depart.

It's up to you, length of trip.