B1,
Whether or not you should stay with AMEX is something you're going to have to carefully consider. As for me, I use Diners/enRoute and have been very happy with the it. It offers delayed/lost luggage and delayed flight insurance, use of DC airport lounges overseas, and other benefits. Not a bad deal for $65. It's accepted at quite a few places, if you look, and I posted some of them on another thread:
http://www.flyertalk.com/forum/Forum70/HTML/000138.html
Where I can't use DC I use my no-fee President's Choice Visa and earn PC points, which equals a 1% rebate.
My mom's friend got a special 12,000 Aeroplan bonus offer by just phoning up and asking for the special promotion application. Sometimes they'll send it out to you, other times they'll refuse, saying it's only sent to targeted addresses. Worth a try, though.