I tend to roam between 400 and 700. Get up high, then drop back down to 400 in one go, and work my way back up. It's surprising how many very heavy dudes are all the way from 200 right up to 800 - there's a huge mix of people that are "steamrolling zergs" as someone put it, and players who have pushed their medal count up well above their means to defend it!!
It's a funny old mix, and I am constantly surprised by it! Today I found a level 56 player in GP age, kitted out, with both wonders built, started on canons and mortars.... with no walls. I mean, they didn't have any freaking walls in their base?!?
I love this game. Heh. Needless to say... he died.