Re: #12 pick scenarios...
It depends on who is available, but I tend to think it's more important to get 2 RBs, especially if you're picking 12th. 2 good RBs and a decent QB (Rivers, Romo) will outscore a great QB and 2 mediocre RBs. Peyton Manning is the only exception, but he's sure to be gone before you pick.
If I were you, I'd take the best 2 RBs on the board in the first/second rounds, then the best two WRs available in the third/fourth rounds. Shoot for a mid-level quarterback and a 3rd RB in the fifth/sixth rounds.
"I prefer books and movies where the conflict isn't of the extreme cannibal apocalypse variety I guess." Redsfaithful