If it's just for sleep then I suppose it might be most practical to use Heliopolis -- go there directly from the airport, check-in or drop your bags and then head to Giza for the afternoon leaving plenty of time to get back in time to get ready for your dinner. The problem which you can see by looking at a map is that the Sheraton, Heliopolis and Giza are in three different directions. There is really no perfect solution so given that I would say being close to the airport would trump all.