Really senior people can stretch out their vacation where it lasts 3 or 4 months, and they're still getting paid. If you change airlines you start all over and have to go through training again. I usually work actual flying about 70 hours a month. That does not include the time that I am actually just getting to the airport and going to briefing, which we have to do before every flight. You really have to deal with being away.
Every month there's a packet that comes out that lists all the schedules and trips available.
You bid for what you want, put down all your choices in the order you want them, and of course it's awarded based on seniority. I know with my seniority what I can usually get. I have had a couple. None of them were super famous. I've had Cokie Roberts on my flight.