Personally, I really like the four man grouping of IT, Bradley, Crowder, and Horford. I want to see what those guys can do as they gain more experience playing with one another. I feel they each have at least 3-4 seasons playing at a high level before they hit a major drop-off point, and the team should be able to retain them during that time without absolutely breaking the bank.
Add to that the fact we've got Smart, Rozier, Brown, and two likely top 10 picks coming in the next couple years, and I'm excited to see what this team can be.
Olynyk may or may not be a cap casualty. Amir, Jerebko, Zeller, and Green are probably gone after this year. Young will definitely be gone. Jackson and Mickey may or may not be NBA players. Yabu and Zizic are question marks (I feel pretty good about Zizic, though).
That core group, though, should have Brad excited. I think the best thing you can do if you can't acquire an MVP-caliber player is put together a 4 or 5 man group that is versatile, talented, and fits together nicely, and then give them lots of time to play together and see what they can accomplish.