Towles is a possibility at C, or maybe an underrated guy like Ruiz, who's definitely available, and plays for a pretty good offensive team. Ruiz will likely get more ABs, I would think, which is the reason I mention him, although Towles has more potential.
I definitely think you're going to need more power to compete, especially with Ichiro in your lineup. Since I think Kemp is going to disappoint this year compared to how high everyone is on him (he's not a .300 hitter, Torre's been batting him low in the order, and he's fighting for playing time with Ethier and--gasp!--Pierre), so you might be able to get a guy like Swisher for him (which would certainly help you in the power department, and with Ichiro, you can take the hit to your BA--just talk up how Kemp is a 5-tool contributor and all that to a potential trade partner). At the worst, see if you can work out a package deal with a 30-HR hitter like Burrell, who everyone underrates (he's also in a walk year, I believe, if you buy into that).
I agree with the previous poster about starting Loney and Pence. I think he's right about Tulo being overrated, but be careful--Hardy's got an illness that they haven't yet diagnosed. It could be nothing, but you never know. Keep an eye on the news, at least.