Are you confident with the centerfield situation? We have three in-house options: Melky, Gardner and Damon. Each has strengths and weaknesses. Melky probably has the highest overall upside (since Damon is well past his prime) while providing solid defense, but he was lost after April. We can only hope he rebounds. Gardner is going to steal bases and play (perhaps) even better D, but will he get on base enough to fully realize that speed? Damon will likely have the best offensive season of the three, but watching his fem-arm is painful and he may not hold up for the season.
There are also free agent/trade options like Randy Winn, Mike Cameron, Rocco Baldelli, Jim Edmonds, Matt Kemp, Nate McClouth, Cody Ross, etc. Of course, they would require prospects or a lot of money (compared to Melky/Gardner) in return.
The X-factor is Austin Jackson, who will start the year at Triple-A Scranton. If he has a great start, and the centerfielder in the Bronx isn't producing, he could get an early call-up.
UPDATE: Aaron Rowand is another possible option.