My suggestions would be all winter OR summer themed characters. You have to pick a side, and get your name on a slot, get an even amount on each "team", so not only do we have one character who wins, but one team.
Brackets should be announced ahead of time, because brackets are fun to look at and make the competition more interesting. I liked the recent contest, but it was the only one not to have a bracket and that took some fun out of it. Since activity on the site is still not going to be where it was at for the original competitions, we should have a loser's bracket.