The 737 is light on creature comforts. To me, though, the pros of having one single huge fleet outweigh the cons. SWA does a lot of different types of flying, and as a mid seniority FO I fly with guys who work 25 days a month and guys that fly 12 MBJ turns a month and never sleep in a hotel.
Anyone can fly any flight. That creates a huge opportunity pool and ways to skin the cat.
I’ve done the long haul over the ocean circadian f job. My body doesn’t like it. I regret not having the opportunity to do it later if I want, but I’ll take the silver lining to that cloud.