As we were flying on American, I checked out their credit card, and obtained one. The first year is free, and I got 50,000 miles for spending some money on it, so cool, but that much FF isn't good for much.
BUT, for 7900 miles, you can get into their lounge, which I did (2x). The second year costs $99 so I'll cancel, but can use the miles for the lounge if we're on AA in the future. I did the same with United but their card gives you two lounge visits a year.
I have a Delta AMEX I use for most things. It comes with lounge admission, but is starting to cost too much.