Just the other night my girlfriend and I were sitting down at the bar in a restaurant with four seats open. Prefering to not sit next to anyone, we asked the bartender, who assured us that it was fine. Soon after we sat down, the party to our right left, and it wasn't an issue. The bartender has a much better idea of the eb and flow of the place, so they're a good person to ask.

I personally wouldn't ask people to move. Having a space between parties at a bar isn't unreasonable if the place isn't burssting out the seams with people. If as you sit down you insist on monopolizing extra seats that other people would like to use right then, you're being a jerk. If you're the only party approaching the bar at that point, I don't see a problem with it.

Perhaps we're all ignoreing the real reason why bars serve food in restaraunts: the dinner for one crowd. And with all this moving about, you seem to be filling up their spaces. Leave 'em for the lonely people so they've got somewhere to eat.

Matthew