I have an unfair advantage on this one as I have spent 12 years working at two very prominent hotels. For the most part I am going to leave out the bulk of the list, and focus on the ones who either left a very good, or very bad impression.
The Bad:
Adam 'Pacman' Jones: An NFL player for the Cincinnati Bengals, Fuck me, he is possibly the biggest tool I have ever met (celebrity wise). barking orders at us, treated us all like shit, and did not tip us a single dime (valet/bell staff). Oh but wait on his final day (every time he came) he made sure one of our three non-white staff members took care of him and tipped several hundred dollars for 10 minutes of work. Fuck those of us who had to pander to him the entire stay, we literally never made a dime from him.
Jon Kitna: Surprise, surprise another (former) Bengals player, now he was not nearly as bad when he came, just over all stuck up. Looked down on all of us, which is funny since he was a pretty terrible NFL player.
Montel Williams: This one will catch people off guard, to the public he as awesome, to the staff he was terrible. He made demands of the employees that anyone short of the hotel owner could not have made happen, then got upset when we couldn't do things like close America's largest indoor water park 4 hours early on a 100% occupancy night so he and his family could have it to themselves.
The Good:
Relson Gracie: One of the heads of the famed Gracie family that created BJJ. I had the pleasure of meeting him when he stayed at the hotel, this wasn't a short hi how ya doing either. My BJJ coach was with Relson, so I got to hang out with him for a bit. The man is amazing, for being one of the most dangerous men on earth, his handshake is delicate, also the man gets drunk off like 2 beers :-P
BB King: I believe BB was the first celebrity I ever met. This was god back in 2003? The hotel I was working for at the time was in the deepest part of our off season, which meant I was laid off (once again, bell staff). I got the call to come in, we had a VIP coming in and corporate wanted me there. When I get to work I find out not only is the hotel dead (3 total sets of guests) but I was going to have to work an 8 fucking hour shift, oh yeah and the VIP arrived early so there was nothing for me to actually do. So I went do to the kitchen to bullshit with Steve, the only chef we had on staff that night. He had brought in some catfish or something he had caught and cooked it up for all of us (the whole 9 employees in the entire building. He jokingly asked if I would take some up to BB King, hell I had nothing better to do so I ran up to the room and asked his tour manager if they wanted to join us. This lead to the 9 staff, along with the 8 or 9 of BB King's group (including BB) sitting in the hotel bar, eating fresh fish and listening to BB King play. Still to this day fucking amazing.
There are other celebrities I would love to talk about meeting, but for different reason (including one set of paperwork I had to sign saying I couldn't talk about the guest) I can't talk about them.