I'm with ExAB on this.

By letting my schedule get a bunch of weekend four-day trips, I can reach stuff that would ordinarily be out of reach for my seniority in base. More productive trips, or weekend 36ish hour layovers in fun places. An extra day or two off per month can also be had by working on weekends because you bypass lots of people who want weekends off no matter what it does to their schedule in the rest of the month.