For the longest time I had my Dock on the bottom. A few months ago I thought I'd try something different and put it on the right side instead. It took some getting used to at first but now I like having it there as it gives me that much more vertical screen space on my 13" MacBook. I've never really liked auto-hiding the Dock.
Bottom all the way. Made it real small, with magnification, but not auto-hide. The hiding is more visually distracting to me than having it there all the time, and I really don't mind the loss of a small amount of workspace.
Right, small with magnification, no auto hide. This way it stays out of the way on my MBP screen and not my main screen (which is to the left of the MBP). If I should just be using one screen I prefer to have it to the side so I get more screen height. I don't like the 3D dock appearance much either.