This last weekend my city was overrun with cheerleaders & dancers - of the teen/pre-teen variety. I also grew up in KC so I'm quite familiar with the FFA convention (one of the best large group etiquette situations I've run across too -they're usually quite nice and polite), etc.... I came up with a few etiquette rules for those times when you might be the member of a large convention (as it seems that the larger the group, the more "power" they weild on the rest of us)...
1. Just because there are a lot of people in your group, doesn't mean you have the right of way. When exiting & entering buildings, using sidewalks, etc. stay to the right so that people walking in the opposite direction are also able to use the space.
2. Do not stop and gather in the middle of the sidewalk. Move to the side so that others have room to go around you.
3. Keep your activities at the convention and not in general public (i.e. cheers in stores, yelling in stores, football in stores, etc. is not appropriate).
The rest of us:
1. For those not with the convention, just because they're a large group, doesn't mean they're not individuals. Do not hold the group responsible for the actions of the single/few.
2. You may have to wait a bit long in line, but they're in line too and have just as much right to be waited on in order. Do not try to cut to the front because you see their group as 1 order so you try to skip.