As far as OL, we have, IMHO:
1) Sitton, a very good starter for years to come.
2) Wells, who has proven this year, playing the likes of Shaun Rodgers, Casey Hampton and Pat Williams, a good starting center, who knows protections and is a crafty veteran.
3) Mark Tauscher, who can probably still go one or two years, and played at a starter's level this, and the last year, and is healthy.
4) T.J. Lang, who showed, IMHO, that he's ready to start. He's not very well suited for the Left Tackle position, but he played well.
That's it. IMHO we have a competent LT, a serviceable at best LG (needs to be adressed), a competent C, a very good young LG, and a very good old RT.
So, the way I see it, if we can get Russell Okung, Antonhy Davis or even Bruce Campbell (as a project), we should get an OL in the first round.
Charles Brown, Bryan Bulaga, Trent Williams and Selvish Capers IMHO would NOT be an upgrade over what we have right now. Not to mention the possibility of getting them in the 2nd round, as well as Iupati, which IMHO is a better guard than those are tackles, and would be an upgrade over what we have, though guards are not as highly regardeds as LTs are.
So, the way I see it, if we're presented to pick between Bryan Bulaga and C.J. Spiller, I would take Spiller. I don't know about Best, though. I don't see him as dynamic as Spiller. I don't even know if he would be an upgrade over Grant, as Spiller could be the perfect complement to Grant, or vice-versa.
Let it be known that I would be far from disappointed if we took any of the OL mentioned here. I just think Spiller would be a better option.
My dream, though, is that either Joe Haden or Eric Berry hurt their feet, perform terribly at the combine, and fall to us. A man can dream... Imagine, Charles Woodson, Al Harris, Nick Collins and Eric Berry? Can you fathom Woodson covering one side, Harris the other, and having Haden and Williams to play as nickel and dime, and being able to eventually develop into probowl CBs? NO MORE JARRETT BUSH! That would be a dream...