Skywest doesn't operate 50 seaters in SEA as was mentioned earlier. We fly the 700/900 for Delta up there and soon ( more than likely) the 19 new 175's for Delta will be SEA/LAX based ( possibly SLC as well but doubtful).
Not sure where we're all gonna park.....

There are several good regionals out there and one really bad one. I don't know a lot about Mesa but I don't believe it is a great choice. Don't make the mistake that I did, stay away from Gojet. If it is in their interest to ruin your career they will. Everything is a money equation and the day Hulas determines that the risk of keeping you is one cent higher than the risk of getting rid of you, then you will be gone.

Skywest has excellent training and you will have the respect of everyone in the industry. They are big in the NW so they are your best bet overall. I would also take another look at Horizon, they are well regarded.