Does a junior base help one upgrade sooner, assuming the 2500 TT requirement is met?

No, anyone can go to any base to upgrade.

Seattle is correct. To clarify, the base and airplane which you are currently assigned has NO effect on your upgrade (unless you intentionally incurred a one-year seat lock). As long as you have the flight experience, seniority, and are not seat locked, you can upgrade into ANY airplane in ANY base. Seniority will dictate that you could upgrade in ORD long before SBA, PSP, or SMF.

So I guess it's better to stay at a junior base and have people above you move out to upgrade quicker?

Yeah, unless that base requires a 6 hour, 2+ leg commute and the trips aren't commutable. Like a certain base in Wisconsin.

Not sure I understand the question...

A junior base is good in that your schedule and QOL will be better (unless you haver to commute). Being an FO in a junior has nothing whatsoever to do with your upgrade opportunity.

Well, if you actually move to your base and want to avoid moving again when you upgrade, a junior base would be good because you could upgrade sooner in the town you already live in. But do you want to live in a junior base? They are usually junior for a reason...

Also some bases are real junior for FO's but very senior for CA's...this is common in expensive California towns because the FO's can't afford to live there.

How junior is DEN, and is their any chance of getting it out of training?

Makes sense..........

I'd say you're looking at about 5 months for Denver. Barring some drastic change, I wouldn't expect it out of training.

You don't need 1000 TT to get hired at SkyWest if you already have 121 exp.