It really depends! Sometimes we're playing through story together (if there's new stuff out we haven't done yet), sometimes we'll be doing fractals (so technically endgame PvE), sometimes we'll go achievement hunting together or maybe farm if there's something we particularly need for something.
I've been considering trying PvP and/or WvW again, but I'm a little scared because I very much consider myself to be a casual player and I'm afraid I'd be holding my team back with my inexperience. :c