Originally Posted by T.J. Bender

So, my advice going forward:
1. Check to make sure seats are available on the flights you want before booking them.
2. If you don't have status on an airline, any airline, don't book the last flight of the night unless you can confirm into a seat assignment at time of booking (you should be able to choose your seat before buying the ticket on any airline that assigns them).
3. If you're flying DL again, check in at T-24, the instant you can, and buy yourself into a preferred seat to make sure your seat request becomes a seat assignment.
4. If all else fails and you're being IDB'ed at the gate, make sure you know the DOT regulations for IDB compensation, and make sure those are adhered to. If they're not by the GA, ask for a supervisor and insist that if you don't receive the proper IDB compensation as spelled out by the COC, you will be forced to file a DOT complaint against the airline naming the gate agent and supervisor as the offending parties representing the airline. I had to make that statement once when flying United a couple of years ago, and much to my "surprise", they noticed that there was still a first-class seat open after all upgrades had been processed, and decided to go ahead and put me in it.