My experience is also that I get 1000x better treatment from the PLAT/DIA line compared to the counter agents at the airport. Also remember that the agents at the airport may be contract employees, and doesn't know the rules as well as Delta phone agents. I've never gotten an airport agent to do better than what the rule allowed. (i.e. you want an earlier flight, book and pay for an earlier flight!)

Even as a lowly GOLD, I was treated very well.