The Celtics one could be fun. Lots of greats have donned green at some point in their careers. As long as you could pick any season from the player you could have a pretty good talent pool to work with.
I think I proposed once, right before these took a hiatus for awhile, of doing a full league historical draft but you couldn't select anyone that was a top 5 pick in the actual draft (you could go to top 10, but that makes it a lot harder to track). You'd probably have to count the early territorial picks in addition to the top 5. That would eliminate a large chunk of the all time greats making the draft far more interesting especially where team building is concerned. I mean no Russell, Wilt, Baylor, Oscar, West, Kareem, Shaq, Magic, Bird, Jordan, Hakeem, Duncan, Garnett, Lebron, Robinson, Ewing, Barkley, etc., but still a very good group of HOFers at least 3 rounds deep for everyone to choose from.