My attitude is basically "screw it." I'm not going to lessen my pleasure just because somebody MIGHT hear. We're pretty sure neighbors have heard us once or twice, but nobody's ever said anything to us, so I'm not terribly worried about it.

We have a roommate now, which does change things a bit. We generally try to confine our activities to times when he's not home, which isn't terribly hard, since he doesn't get home till about 2:30am six nights a week. If we do have sex when he's home, we put music on or wait till he's watching a movie so he won't hear anything.