I came on board late last year. I went to the new IAH base as soon as it opened. The answer to the question of what base you will be assigned is difficult to say, even for the folks in the company that work in that department. Anything except MIA and IAH are very well possible, with the most likely candidates being CMH, LGA/EWR, IND, and PIT. But, within 6 months from DOH someone from my class was at every base.

Unfortunately, captain base seniority is different. As of now, the earliest available upgrade is at EWR or LGA and is currently happening at 2.5 years from DOH. PIT is available a few months later. IAH and ORD are (currently) the most senior, requiring 4.5 years to get there.

Life as an FO can be pretty good pretty quickly, but once you upgrade getting back to the base you prefer and getting off reserve is more difficult.