With Texas likely out of the running for Fielder, it's really down to the Cubs and Mariners. Between the two of them, I really like the Cubs' chances unless some team comes out of nowhere and grabs him.
I think it depends a lot on what's important to Fielder. If it's getting paid, I think it might be Seattle. If it's about winning then neither Seattle or the Cubs are contenders.
Let's take a look at sleepers from a winning perspective.
Giants - Need a big bat to compliment their great pitching. It all depends how they see Belt
Dodgers - Definitely could, but I don't see any cash there
Rockies - What a sleeper that would be. Helton's time has come to pass, Could they carry Helton for the year (assuming his option has been picked up)
Diamondbacks - Great fit on such a young team
Cardinals - Replaces Pujols, could be offered same contract that Albert turned down
Brewers - No one thinks he's coming back, that's a true sleeper right there
Reds - No need with Votto
Nationals - Morse came out of nowhere to hit 31 dingers last year but he'll be 30 on opening day. Could be the last veteran they need to be perennial contenders
Braves - Freeman is their guy for the future, no need
Phillies - Ryan was the first big signing at 1b, no need
Marlins - Man, crazy dollars there. They could jump in on it.
Yankees - Texeira, no real need there
Red Sox - Gonzales, no real need there
Rays - Another team that would be a great sleeper and make them on even par with the two big boys
Tigers - Miggy, enough said
Angels - Albert was their choice
A's - Would they be a contender with a bat like Prince?
Rangers - they just dropped a ton on Yu, but with Hamilton a FA after this season taking Fielder still seems like an option.