My favorite contemporary master of this (mainstream comics division) is J. H. Williams III.  Promethea is pretty much cover-to-cover lushly illustrated formal play, and more recently, his work on Sandman: Overture is endlessly inventive eye candy.  Without a doubt, sometimes you have to work a little harder to track the story flow, but in the context of these two very thematically-dense works, it's less of an issue (though I'd bet if he was doing similar stuff on Batwoman it would have been out-of-place).

For a single panel, this is up there:

If you're judging creativity solely by how uniquely a page is laid out, then maybe it doesn't fit on this list.  But the sheer volume (and incredible quality) of creativity that went into every page of that book places it close to the top for me.