I just have a Visa through my credit union. I use to have an Amex blue, but I paid it off and closed the account. I since decided I'd like it again, but every time I apply, they reject me. I think they're like a woman scorned.
I've been considering a good 2nd (back-up) credit card, but not sure what would be good. Maybe another Visa...or maybe Diner's Club.