MDW is the largest base . BWI is most junior followed by LAS and maybe MDW. DAL is very senior and it is also the smallest base. To compare, MDW has roughly 1700 FA's while DAL has a little over 900. My base, MCO, has roughly 950 making us the second smallest base!
TPA has been announced as a possible 717 base for pilots. Because all FA's will be trained on all aircraft, there is no need to have a separate 717 base for FA's. A FA's pairing can consist of a flying on both the 737 and 717, whereas pilots need separate pairings and lines depending on the aircraft they fly.