the arenas are always fun, if you can find people to do them...1v1 is the most common due to the lack of players that queue...
even the arcanium arena has lost some players...
imo, best thing to do, get a lvl 28 alt/3rd class, dirty stat it to about 10k HP, pwn arena...not hard, and a ton of fun fighting other "twinks". the big thing with lower level twinks is u can only get so good of a weapon(and thus, max damage), but you can stat the gear to the sky, enabling more team-based, strategic fights, not the 1 hit fest that is higher lvl pvp...
pvp wars guildwars etc) 
