If Delta is hiring, they have pretty good benefits. Full and part time employees get full benefits. You and your spouse and children get full benefits. If you do not have a spouse, you can choose a travel companion who pays reduced rates. You also get 8 buddy passes per year to give to friends for reduced fare flights.
Its based on seniority, but usually it doesn't matter... They get full benefits after 30 days and it is completely free in the USA, and you pay only departure and landing taxes when traveling internationally. You also get first class when available, which is usually on almost all international flights in my experience.
Also, many airlines have counter to counter agreements with other airlines at your airport. This means that you can fly other airlines for free as well. Ask about it when applying/interviewing.

Nearly all airlines have ID90/ID96 or ZED fares. This means that you get 90% off, or 96% off of the lowest fare on almost all other airlines.