While conquest is enjoyable and WvW has its place, I think that other games such as Capture the Flag would draw a fantastic crowd, or toss in a Take the Keep game as well. Not the WvW crap, but in a structured PvP where teams try to take another team’s keep and win if they slay the other team’s lord.
I played RoM for a while and their PvP for Guild Siege was so popular the servers would crash.