Phoenix
(sorry, got interrupted). Some gentlemen are not encouraged to come back, but that's unusual.
As far as what makes a great client--being polite and respectful are number one with me; also important, especially at the first visit, is to let the girl take the lead to set the pace and comfort level.
If you let her get comfortable and cozy, your rewards will be plenty. 
I think the best part for me is getting to meet different people, with their diverse personalities, occupations, and hobbies.
It's fun to be with an outgoing, personable guy; then refreshing to next be with a shy one where you need to coax him to be comfortable.
I'm now a veritable fountain of triva and factoids about jobs, sports, hobbies, current events and the arts.
Thank you, gentlemen, for making my "job" ever so enjoyable.
I'm sorry to hear that Coyotefan2 hasn't come across anyone who has shown him that they genuinely enjoy what they do and genuinely enjoy him. Agreed, it seems that the majority are "all about the money" and make some clients feel like they're on an assembly line... but there are some of us who really appreciate and care about our clients.
Personally, I enjoy a client who respectful of me as a person, happy to be with me and open to what I have to offer. I love being in control and being able to "have my way" with my clients but I always appreciate and encourage feedback. That is how I learn what is most pleasurable and satisfying. It is the begining of what becomes a special 'relationship' between me and my client. We share very intimate time together and become more intune with each other during each session. My regular clients are my friends and when money is tight they know that I will work with them. Recently one of my clients lost his job and called to talk about it. He told me that he could really use a massage but that he couldn't afford to tip much. I welcomed him to come see me and after his session, when he usually gives me the massage fee and tip, I told him it was on me. I did it because I consider him a friend. I've done similar things to many other clients because they are my friends too. The most special thing to me is that they have always made it up to me as soon as they could...without me ever expecting it. Guess I'm their friend too 
My clients didn't come to me and don't stick with me because I'm some young, beautiful, slim model type. They come to me because they know that I love what I do and it shows in the way that I do it and the way I make them feel. They all know that, "if I'm not having fun, nobody gets to have fun". ;o)