This is absolutely no need to trade up. There is plenty of talent there at #12 and we should just take BPA. If you trade up, you are doing is "for need"...period. There is noone, especially an LT, that is so great we need to mortgage the future for him.
Personally, I would rather drop down a couple of positions and pick up a high third, or down a little more and get another second. There are a whole bunch of players with "about the same talent level", and i would be happy with any of them. Getting another 2nd or 3rd would be great in this year's draft.