Mainly I'd just love to give Rondo a guy who is 6'11''++, reasonably quick and athletic, energetic, a solid shotblocker (for when Rondo matadors ball-handlers to the rim), and who can roll to the rim and finish on the pick and roll very effectively.
Anybody who fits that description would probably play at center and be an All-Star, so it's unlikely to happen. But it'd be great.
Indeed, somebody like Marcin Gortat or maybe even an Anderson Varejao or Joakim Noah type would more or less fit that description. I think a player like that would go great with Rondo.
Basically, give me Perk back, only taller, quicker, and with much better hands.