Well, if you know in advance what you'll be using the miles for, that makes the calculations easier. If you use 25K for a $300 ticket, that's 1.2 cents per mile charged. Many folks here cringe at the idea of using miles on an affordable domestic R/T, but if that's the route you fly, then that's where the miles go, right?

FWIW, when I've checked domestic RT's on AA using miles, between DFW and mundane (sorry) places like BNA, I'm almost always able to find something for 25K, except maybe short notice holiday weekends.

The AA card from Citi would work for you, but consider the Starwood Amex instead. Lower annual fee, and xfers of 20K miles get you an extra 5K bonus.

Bottom line, 50K in charges is easily enough to justify paying the annual fee. Whentehr it's better than whatever cash back you get currently, well, you'll just have to crunch some numbers.