I've been at SKW for just over 3 years on the CRJ. Here's the order of where I would sit in each CRJ domicile from being most senior to most junior. Depending on where you sit, the order might change slightly for some people. But it'll be about the same in general for everyone as long as we continue to hire.

MSP
ORD
IAH
COS
DEN
LAX
TUS*
PHX
SFO
FAT*
PSP*
SLC
PDX
SEA

*TUS, FAT, and PSP are very small domiciles. TUS has only 16 FO's for example so that probably skews my percentage. Pretty much, SEA is the only domicile I can't hold at all still. As a new hire, I'd say you can hold any of these CRJ bases within a year or less, except for PDX and SEA. They only just let a couple guys junior to me into PDX recently, but they have succumbed to a life of reserve. But if you live there, it's probably an easy thing!