I think you stumped us there. I'll try for a short answer:

If you're hired into the E175, you can have any base you want as long as it's Seattle. For Q400 FO's, the junior bases are Medford and Portland. Spokane, Boise, and Seattle tend to be more senior. Most of the FO's are getting their base of choice within one year.

As far as the "quality of life" issue, that's impossible for me to answer because I don't know what your priorities are. I expect the jet schedules to be much better, but we're currently way overstaffed on the E175. At the present time, the Q400 pilots are flying a lot and the jet pilots are mostly sitting around. In my opinion, the biggest single factor that will make or break your "quality of life" is living in base versus commuting.