Credit card question

[junkerman123]

So I've been using one credit card for the past 6 or so years, my trusty Citi Dividend Platinum. However, lately I've been thinking that I want to get an American Express card, if only to keep it around for years and build up brand loyalty. Do you think this is a good idea? What American Express card/services do you recommend (obviously no annual fee)? Would having a card that I don't really purchase anything on affect my credit score one way or another?

P.S. Since I'm signing up for a new C.C., anyone know where I can get some freebies for signing up for a card?

Thanks