It's not often you get better by "going old," but in the Mariner's case, that may be a reasonable place to start. Their DH slot was a total mess last year...no power, no on-base percentage, automatic outs and instant double-plays galore. What to do, what to do??? As counter-intuitive as it might seem, signing Ken Griffey, Jr., as DH could be a sensible first move.
Griffey knows how to take a pitch, draw a walk, get on base, and hit from behind in the count. He's got a strong OBP (better than almost every existing Mariner), and better power than almost every existing Mariner. He doesn't hit for the average he used to, but in every other category he still brings something good to the plate. On top of that, his numbers were impacted by a bad knee last year, on which he has since had minor surgery.
Add to the above his existing marque power and history in Seattle (and the current club need to generate some kind of interest and enthusiasm from a bored and disgusted fan base), and a Griffey signing seems a reasonable thing to consider. The park was literally made for his swing, as well. If he's available for a reasonable price, this seems like a deal that could be done, should be done, and is something that will actually make the team stronger.
On another front, let's go with a counter-intuitive move of trading within your own division, and send Jarrod Washburn to Texas (who needs pitching) in return for Hank Blalock, who moved to 1B last summer. The M's had a HUGE hole at 1B last year, and could use Blalock's power and relative youth (28) in their line-up.
Adding the power of both Griffey and Blalock gives the M's the ability to put rookie Wladimir Balentein back in left field without demanding power and high performance immediately. He's shown the ability to adjust when given time, and it seems way too early to give up on him.