Plus, at the risk of flogging an already-dead horse, SPG Amex gives you more flexibility and a higher yield than typical mileage cards.

Best case: you use some or most of your points on hotel stays. It's relatively easy, even for a modest midscale guest at Sheratons and the like, to justify Starpoints as 3 cents apiece in real cash return. If you are already spending a lot of money on higher-end hotels, the returns can be even higher.

Worst case: you can't find enough need for hotel stays, and you convert them to air miles at at least the same rate ($1 - 1 mile) as you'd get with the airlines' own cards. And although I wouldn't advise burning large chunks of Starpoints on miles, if you have to do it in 20k increments, you get 1.25 miles/$.

You have many airlines to choose from. The only major "catch" that might affect some is that UA is not on the list of 1:1 carriers. (I think UA is 2 SPG to 1 mile, an absolutely horrific conversion rate.) But...as long as you aren't married to UA, that's not a showstopper. Sounds like you're talking AA. They are on the list of 1:1 carriers.