Don't miss the Old Faithful Lodge. It is a wonder to see all the log work. Since you are camping, if you can work it out, see if you can get a leftover cabin or room there for a shower one night. The plus side of that is that you can only get reservations in the lodge dining room if you are a guest. You didn't say how old daughters are; a bit older and they appreciate fine dining more. One of the best meals ever for the wife and me, complete with wine and dessert for a reasonable price. We have never made it to Mammoth yet. Thermopolis has an old hotel if you are so inclined with a private pool.
I am jealous.
