Hi Queenbee
i went to egypt last year with my parents we did cairo and luxor and we did the trip in September when it was hot, so in December it will be better and cooler.
If you have trouble with confined spaces dont try Great Pyramid as you are on your hands and knees most of the time. It can get very musty as well. The spce is very small.
Around the corner from the Great Pyramid is Solar Boat Museum, you have to wear shoes not to damage the floor.
Try and get to go in King Tuts one you have to pay extra about £7.00 on top of the price of you are going to Luxor. Another temples which are wide open in Luxor are Karnak, Luxor and most of the Valley of the Kings. I couldnt in a couple of tombs as i was feeling very ill due to the heat and waited outside in the shade.
Another tomb which is wide open is Queen Hatsheput Mortuary Temple.
I dont know if your family like museums. The Luxor Museum of Mummification is quite cool bit upset of no brain scoop. Its about £3.00 to get in.
My favourite in Cairo is Egyptian Museum right near the Marriott Hotel, very open you can take water in with you. For the £10.00 extra i would pay to go and visit the Royal Mummies room
The Room have Seti and many friends, its all air conditioned to keep to an exact temperture, they are hoping of having Queen Hatsheput mummy as well.
Hope this all helps