Ok, that is what my calculations came out to as well. But it was extremely linear, steady - no remarkable periods of quick movement for the entire 35 years based on current numbers available (this website). I ran numbers for United, American, Delta, Southwest, and Fedex too, and based on those, after about the first 5 years, I'd have roughly 15-20% higher seniority, relative to Alaska, at all of them for the next 25 years, after which point it levels off and the last 10 years at Alaska would be better. The advantage Alaska has is that I won't have to commute my entire career, and if I do, its RDM or MFR to PDX/SEA.

I welcome critiques to my assessment here. There are probably things I am not accounting for.