Two general items up front: 1. Restricted free agents aren't real free agents. Anyone worth keeping will receive a high tender (1st and 3rd round, 1st round, or 2nd round picks as compensation) and it won't cause any salary cap problems in an uncapped year. "Teams have the leverage." Other NFL teams aren't going to offer a big contract and surrender a high draft pick. 2. The best thing the Green Bay Packers could do in free agency is resign all their current free agents.
The top two unrestricted offensive tackles are the Packers own: LT Chad Clifton and RT Mark Tauscher. So says Pro Football Focus, and Walter Football, as two examples. The downside: both players have dealt with injuries over the past two seasons and logged 10+ seasons in the NFL. The upside: they are the best the unrestricted free agent market has to offer, neither should attract a huge contract, and they both played well late in the season. With the exception of OL T.J. Lang, there is nobody else on the current roster that is good enough to play at either tackle position, so resigning both of them is important.
RG Josh Sitton is solid, and he started every snap in 2009. Unfortunately, the top 2 unrestricted guards play on the right side, Bengals G Bobbie Williams and Patriots G Stephen Neal. Signing either would require a move for Sitton to the left side, and I'm not sure that's a good idea. Plus Williams and Neal should expect big money. LG Daryn Colledge gave up a ridiculous 9 sacks last season, but his starting job was never in doubt either. The team seems to love C/G Jason Spitz for his size, on-field play, and versatility. The Packers should tender them both at their original draft spots (Colledge, 2nd round, and Spitz, 3rd round) for just over $1 million each. That tender should scare off most teams due to Colledge's poor 2009, and Spitz's season ending back injury.
Who should the Packers should sign? I'm not in favor of signing anyone from another team, but after Williams and Neal, I'll point out two other names.
Texans LG Chester Pitts. He'd be a pursued free agent this year, except he destroyed his knee back in September. His value before the injury was even in doubt over at Battle Red Blog. His knee might be so bad that he might not end up signing anywhere.
Browns RG Rex Hadnot. While he played mostly at right guard last season, the Packers could ask him to play on the left side. He's viewed as a backup in Cleveland, but he only allowed 2 QB pressures in 2009. While there's a lot of room to improve on Colledge, there's a lot of risk in asking a backup RG to become a starting LG. I'm not in favor of signing Hadnot, but it might be the best low cost free agent signing the Packers could make for the offensive line.