I was thinking that an addition to the level editor could be a mini map. What I mean by that is, that if there was a mini map that updates automatically (only for the level or if you want whole map) that shows up in the level editor so you can see what you're doing on the map. and it could be re-sized, moved and minimized.
Just an idea, cause I find it rather annoying having to play through a level to see what it looks like on the map :X