He's been great, they love him there, and the team needs him with Ortiz fading.
If the plan is to sign Holliday they should just trade for him. The cost in prospects will be somewhat offset by the picks they will retain by not signing him as another team's FA, or the picks they will get if he bolts. I wouldn't though. He's proven that he's nothing special away from Coors, just like his splits suggested.
The other guys don't do much for me. I'd probably look to FA for a 2b, a Freddy Sanchez or Iwamura type.
IMO they have to trade if they want a middle of the order hitter, and that probably means breaking off some pitching to someone.