In contrast to another's post earlier, I find the international long haul much easier than domestic next day type of flying. With the long haul, you get 2.0 to 2:45 rest periods and I find that really helps during the flight and it's much easier to get up, move around, and cook some food than at the pax carriers. The layovers are typically 24 hrs or longer so you can catch up to a certain extent - I often get get numerous periods of 8+ hrs.

Domestic nights I find difficult. IF you are on time you can get 2 maybe 3 hrs of sleep (if you are really lucky) in the sleep rooms then back to the hotel no later than 7am (some locations are earlier). I just can't sleep more than 5 hrs during the day regardless if the hotel is quiet, dark, and cool. Then I'm all out of whack during my days off resulting in chronic fatigue. International, I'm tired during my trips and about two days afterward. Ironically, at the regionals I used to be able to fly standups (high speeds, momma trips, whatever you know them as) without much issue. I think the key is to find what you can do easily and try to bid those schedules. The hours of operation at FX/UPS are challenging but could be flown without much fatigue IF scheduling limits and practices would be considered by either company.