I wish CN wouldn't have chickened out in 2011 and would have let Adventure Time and (especially) Regular Show be the sort of transition shows they were supposed to be (aimed at 12-14 year olds instead of the 6-11 demo they were both "officially" targeting). They were the last two to air each night before adult swim, RS had "crap" and "pissed" in its early episodes' dialog, AT had that line in that song referring to Marceline as "that sexy vampire lady".
CN clearly had no problem approving the scripts/storyboards with this still in, yet less than a year after they started airing though CN censored those episodes of Regular Show (don't know about that line in Adventure Time, but they never allowed anything that """risque""" again). I think both shows, but especially Regular Show, were severely neutered when they had to tone down their writing.
My point is back in season 1 of both shows they seemed like a perfect transition to Adult Swim and I'm sure that's what CN management was thinking when they greenlit them. But because of CN's backpedalling, having either show on AS now definitely feels out of place IMO.