Casual pass time?

I'm going to be living out of boxes mostly and traveling over the next few months. However, the MMO "itch" has struck again and I'm looking for a semi-casual, laid back, F2P game i can play sporadically but still feel some sense of fun, progress and immersion.

I did this once before after SWG was released and as a result, never really got back into the game since too much time had passed between the moves and playing. The Repopulation is on its way out now and I don't want to commit the $50+ price to it to alpha/beta test a game I won't have time to be around for like I did with SWG. Once I settle back down, I'd like to get into that game though.

So for now, does anyone have any good recommendations for a more casual MMO that I would only need to play here and there in order to enjoy? I'm thinking F2P is probably the way to go for this time, but not a MOBA... I hate MOBAs... can't stand 'em!