Kuperama, I stayed at the Mara Serena. It was fabulous. Very funky interior and design. One night we were up late outside of our suites when a guard came by and reminded up that we were in the middle of the wild and should go inside. It is funny how easy it is to forget that the animals are real and that you are in their territory. I've also roughed it in the Serengeti and the next morning we found lion prints around our tents. Very exciting! Looking back... quite insane really! 
It is easy to forget... and Amy, because of the 'structure' of safaris, they may seem 'touristy,' but I didn't find them that way. I liked the idea of going out on a game drive on our own, then coming back to a nice, clean place where we didn't have to worry about food or (too much) about animals. In Africa, I would say you generally want at least some place where they are properly set up for tourists, and when I went with my parents, they had said this time (this was their second time, they loved it so much) they had made a point of going to places that weren't as touristy as the first trip. And in fact, it was at Mara Serena, when we sat down to lunch the first day, not a moment after I set a roll on my bread plate, as I went to reach for it, there was a monkey with his hands on it, ready to take it! I let him.
And jklm will correct me, but I think you are right, I think it's now the beginning of 'the rainy season' in Africa - so you certainly wouldn't find many tourists, but I don't think it's the best time to go.
