Trips vary by base and other factors. Mtx bases like ORF had more early shows on day 1 and sometimes more day trips. Generally most lines are 4 day trips with 3 days off. If block hours are down or staffing is up there will be more days off. There are some 3 day trips thrown in as well but most are 4 days. Sometimes they will have CDO lines where you fly an out-back overnight with the rest period during the day. Lately there have been only 2 lines of those in PHL, but it can change as time goes by. Days off will vary with staffing. Most months there will be a bunch of 12 day off lines, a bunch of 13 and 14 day off lines and some 15-16 ones thrown in. As always, seniority makes for better options. With creative bidding and not commuting you can make a pretty good life.
And yes, historically we run pretty lean so dropping trips is hard to do unless you can find another pilot willing to pick it up, but there is usually enough open time at 1.5 or 2x pay that it probably won't happen often. With the constant hiring and flow out the door I don't see us being fat enough in the near future where we have lots of reserves sitting around for very long.