The dock on my 1024x768 iMac display (I think screen real estate may have a significant influence on people's preferences): Right side, centered, icons about 24 points, with just a touch of magnification (enough to give me extra visual feedback about which icon the mouse pointer is over).
I'm a somewhat long-time Mac user (since '96) and when I first moved the dock to the right, I figured I was placing it in a position somewhat similar to where the pre-OS X application menu would drop down. That's kind of a weak reason, but I left it there because screen height is already more constrained than width on this little screen. Funny thing is, in OS 9 which allowed you to tear off the application menu, I'd always place it along the bottom (but the icons there were only 16 pixels).
I'm also a proficient Windows user, and I just keep the taskbar on the bottom. I tried it on the top and on either side, and the thing is just too clunky and... different to fit there comfortably. For me. I personally can't stand hiding either the taskbar or dock. And I'm too lazy to seek out, download, and especially get used to something else like Dock Drawers or whatever those options are. <shrug>