I would always trade down if the deal is good for us. My gut feeling is this years talent is thinner then it's been in the past, especially at QB. There are no elite QB's, and not much separates the top QB from the 6th ranked QB. I would never reach for need(cough....Mike WIlliams). So when trading down, I would try and pull a Pats move and gain an additional #1 next year. Something like trade down to 30, and pick up an additional 2nd, and next years #1. That allows you to take a shot at a QB in the first 2 rounds, and two number 1's next year just in case.
So if I was GM- I sign Levitre and Franchise Byrd, or vice versa. I sign Dave Nelson. McKelvin, Kyle Moore. I target Brian Hartline and Martellus Bennett as free agents. I draft 2 QB's, 3-4 LBers, pass rushers, and secondary help...