You're golden after a year of captain time in a 121 operation. Pinnacle would be a fast way to do it, however, there is a possibility of a strike, which could possibly delay you building your hours (either your 357 hours required to get up to 3500, or your captain time to get to a major).

Mesaba would be a safer bet, however, you also have to consider that you're pretty close to being competitive at NWA mainline. If you go to Mesaba, I'd imagine you'd have to stay in line if they finalize their flowthrough...otherwise the company would probably be reluctant to hire you because it might be in violation of their flowthrough agreement since you stepped over the guys ahead of you.

If you went to Pinnacle, upgraded quicly to Capt, and had your 121 PIC time up, you could go to NWA whenever they gave you a look...

That's the backside of flowthrough agreements that no one ever talks about--the fact that it turns getting hired at the major/parent company into an issue of seniority vs. qualifications. You're close enough to an NWA mainline job anyways, that I wouldn't risk having to wait in line at Mesaba if I were you.