Based on my experience, the person who answers the phone is not a "travel agent" - for example, they don't understand basic segment construction, have no access to their Sabre GDS, cannot issue or modify tickets, or do even the most basic tasks in any way different from what you can do online yourself. I've had to escalate in order to get someone who can comprehend these things and get more complicated tickets or routes or changes done for me - and they still need to be queued to another desk for ticketing.

What I would expect from a Platinum Travel Agent is sufficient training and experience to understand more complex ticketing and routing concepts, airline and hotel product knowledge, destination knowledge, and direct GDS access to create, price and test itineraries on the fly. That's what my clients expect from me, but then again they don't need to pay me $600/yr. The average person is better off skipping Amex and going with an in-person agent at AAA and then getting the points back after purchase if they don't need the 35% rebate.