I went with my wife and our two sons 2 weeks ago, we went on the Salamis Glory, not a bad ship in the harbour but too small for an enjoyable trip, bearing in mind the weather's changing now, on the way over there was a bit of a roll, my wife, and many others didn't enjoy it but not really a problem, coming back it was terrible, the ship was all over the place, this time my wife, stepson and many that we spoke to when leaving the ship, had terrible sea sickness.
However, the ship wasn't the point of the trip, and we did the trip to the Pyramids, Museum & Nile cruise....
It was wwful, the Museum was more stress than it was worth, you could learn and see more in an hour online than you would at the Museum itself, chaos doen't begin to describe it, the Nile "cruise" is a trip on a floating restaurant, by the time you finish lunch you are back where you started, the Pyramids are awesome and worth seeing but the hassle you get from camel riders trying to get you on a camel make it a PITA, not to mention the camel sh*t, at the nearby Sphinx you get hustled to buy T-shirts ect every other yard.
On the tour bus you get told to buy nothing until you get to the "Official Shop", right at the end of the tour, we saw the guide getting her commission just as we were leaving

, the bus driver was talking on his mobile with both hands off the wheel for more time than I felt comfortable with and the armed guard on the bus (who was licensed to kill, according to the guide) fell solid asleep
My advice; fly to Cairo, take a taxi to the Pyramids, fly out on the same day.