I think that all of the above ideas are great!
We could also have some kind of adventure map to do for fun. Maybe we could have some kind of guild/grouping system that will let us do the adventure maps together or something. For example, one person would have to stand on a pressure plate and one person open a chest.. idk... like... Co-op adventure maps!
There could be a creative world map for building. It's hard knowing exactly who griefed but maybe there could be a few players that patrol the creative world map once in a while to check if anyone griefed the map and rollback damages.
Lets start off fresh with a few new plugins, a new SMP map, mcMMO levels, and money!
PS Bring all your friends to play on Boss!