I would keep the following in this order-
1) Gonzo Round 5 - 1st round talent at a 5th round pick
2) Pedroia Round 8 - 2nd round talent at an 8th round pick
3) Garza Round 16 - Should have a HUGE 2012 campaign
4) Carlos Santana Round 25 - At round 25, this is too good to pass up. I imagine you can keep this guy forever with the price tag (and inflation)
5) Ian Kennedy Round 15 - I like Kennedy and think he can post top 15 SP numbers in 2012. At round 15, this is a bargain. Especially with IP as a category
6) Heyward Round 20 - Good value here, but read below-
The only problem with this list is that you are throwing a lot of talent back into the draft (Braun, Kinsler, Bruce). And if a lot of other players have rounds like Gonzo or Dustin (good players at bargain prices), then I doubt there is going to be much talent in the draft. So if you don't think you can get a Braun or Kinsler type of player back in the first 1-3 rounds, I would probably cut Heyward for one of them.