I'm not up on the higher-end, Strip buffets, but Roy's list looks about right from what I've heard. I might put Wynn above Bellagio, but a minor issue.
The only question I have is that Planet Hollywood used to be very highly rated. Did Harrah's end that?
I completely concur with Roy over his assessment of both Rio and Paris. I was greatly disappointed by my one trip to Paris a couple of years ago. And they didn't even have nutella for the crepes. What's with that?