CTF with 4 teams sounds a little bit confusing. It would also require lots of players. Also, the game would take too little time, since each team would be able to capture flags from 3 different teams. No, just no.

I've seen decent maps on Elecrton's server. I don't know if he made them or he downloaded them from J2O, but they're perfect for "Frog Hunt" gamemode. The Frog Hunt is the only multiplayer gamemode I like beside Co-op and I can't recommend it enough.