I'll say this - it's going to be awfully tough for any team in a situation like Chicago or Sacramento to pass up a top-2 pick in this draft.
That being said, I'd give up our Brooklyn pick and ONE of Crowder, Bradley, or Smart for Butler, but not two of them. I don't think someone like Butler moves the needle enough for us to justify giving up two of those guys and a high pick. I've consistently said that Crowder, Rozier, and the Brooklyn pick is fair value for him, and I'm sticking to it.
Now someone like Cousins might be different. Not only is he arguably the best center in the game, he fits much more of the criteria that we're lacking and need than does Butler - overall scoring, size, rebounding, post presence, and a position of need.