Our team (812) is extremely spirited, and is guilty of many of the concerns that people have brought up. This year, at the SoCal regional we stand at field level, as the stands are elevated, so others can see. Past years, we stand to the side, or the sections where people aren't directly in back of us. We try to be sensitive to others' problems with our cheering or what not.
The majority of the team cheer, dance, and make tons of noise.. not to irritate people, but because we're infatuated with FIRST! Some teams have come up to us to ask us to cheer for them, or with them, and we always cheer for Team San Diego teams... so we end up always cheering throughout the competition.
To us, it's only appropriate to stand and applaud while a team is receiving an award. It's also much easier to high-five the team members that win.
Now, it's much easier and more natural to cheer standing up than sitting down. Cheering makes the competition so much more fun, and keeps you involved, rather than sitting down and watching.
Most of the center sections are very spirited, so most teams who like to concentrate on scouting or just watching should keep that in mind. Again, at the SoCal regional, we went down from the elevated stands to stand and cheer. I'm not sure about other regionals, but it'd be nice to have such an area. In any case, most teams that cheer are usually gracious professionals, and would be happy to accomodate, or reach some sort of compromise... as long as you approach them with your concerns.