I once flew LAX-ATL in 1996 on the MD-11. It was a flight that only operated once a week (Mondays) because Delta's LAX-NRT service used to be six times a week (except Tuesdays). So, I think rather than having the aircraft sit idle at LAX for a day, it was reasonable to take it back to ATL for servicing.
Even though the flight was published in the schedule, few people booked it. Perhaps it was partly due to its poor scheduling - 5pm departure and midnight arrival so connecting traffic was not possible. On the flight I took, there were no more than 50 passengers.
The most remarkable experience was the short take-off roll, because of the light load. Overall, inflight experience was certainly different (and more comfortable) than sitting in the "friendship seat" on a fully booked flight!
I've also flown Swissair ZRH-LAX and Delta LAX-NRT on MD-11s but this was the most memorable because of its unusual circumstance.