i actually was an Amex financial advisor a few years back...using amex is a bit better than using a broke, as they work a bit harder getting an overall plan for you. so, the $500 bucks pays basically for them to do asset allocation, look at what you make, whayt you owe, what you need to save for, etc. and develop a nice overall plan for your entire financial health. lots of brokers just say "how much do you have to invest", and ignore the rest.
also, they do sell lots of non-amex products...so, i would say it is a great idea, especially as you are likely in a financially diverse stage of your life. incomes and needs will be changing a lot over the next few years, and the advisor can really help you develop a good plan to get you a few years ahead of where you may be on your own.
some advice: go with the mid level advisor, that has been there a couple years. he is still hungry enough to really work for you, and has been there long enough to know the business. the field has a high turnover, so be careful with the really new folks. also, ask about commision free products. there is almost always a good, commision free product that will fit your needs. he is working for a fee (a small fee for 1 year of work though) so don't let him try to fleece you with a ton of commision products. there are some that you will likely need, but not all of them. also, listen to the insurance pitches. sometimes, insurance products are great deals. these guys want you to be rich and safe over the years so listen to them.
good luck!