I work for one of American Airlines wholly owned regionals. We get free standby travel on any AA flight - with an app thet lets us check loads and list ourselves. Free travel also applies to partner, kids, & 2 parents (own, in-laws, any combination). Same priority as AA mainline, too. AA doesn't use seniority to grab flights - it's via check-in order. Up to 6/yr higher seating priority flights too.
We also get buddy passes, at a slightly lower seating priority at imputed tax cost.
Cheaper hotels (at the rate the company pays) & other accom. deals, car rental, discounts, a bunch of shopping deals incl. cars.