Sign em all! Lol..
But yeah.. Clady would be my obvious #1 choice if he ever hits the market (Which doesn't seem likely). Sounds like Jake Long really could become a free agent this year, but then the question becomes if he does, is that actually a bad thing? Why wouldn't Miami want to re-sign a perennial pro bowl player? Franchise LT's just don't come available because teams know how valuable it is to have one. I'd caution myself a little bit. He hasn't played very well this year, and it's obvious that his back isn't allowing him to play as well as he's accustomed to. If I'm the Bears, I do some heavy research and figure out if he's worth the risk.
Further more, if the Bears can come out of free agency with 2 starters on the offensive line, they have come out of it looking really good. You need at the very least 1 sure fire guy, and would be lucky to get 2. Then take one at some point in the draft and suddenly the line could be looking much better.