Staying Positive Around Negative People

Over the last year I've been working on keeping a Positive Mental Attitude (pma). Its been, at best, a great way to live and, at worst, a constant struggle that has at times made me want to start drinking again.
The hardest part is, obviously, other people. I find that most people are, on the whole, nice and respond in the same manner as I treat them. A few are fucking assholes. How do you deal with assholes and keep a pma? I mean it's hard to keep pma when fantasizing about beating their brains in with a 5lb can of beans.
I guess the best thing to do is avoid them altogether. Just cut them out of ones life. I've done this without even realizing it. There's a few people that I no longer talk to or hang out with and haven't done so for years. People that bring me down or are so bent on creating unnecessary drama and conflict that their friendship was simply not worth the effort. So a fair number of folks got cut from the friend list. But what to do about people that one can't just flip the bird to and hit the eject button? There are co-workers, family members and others too close in one way or another that can't just be left to stew in their own putrescence. This is where I am. Trying desperately to maintain my stoke and not get caught up in the bullshit.
I guess the answer is the same as its always been. Treat everyone how you wish to be treated and never expect to be treated the same. Expectation is the root of unhappiness. Buddha taught this and it stands true now. If I expect people to treat me the way I want them to and they don't, I get upset.
So I have to learn to let go of the desire to be treated the way I feel I deserve. Fair? No. But that right there is the problem. I feel its not fair. If I can learn to let go of the idea of being treated in a way I feel is "fair", I can let other people do what they will and stay stoked.
So basically, no body gives a flying fuck about the way they treat me and it doesn't matter how I feel, so I may as well choose to be happy. And there's the Zen in my stoke.