If ATL, then DL. Just be sure to get your FF number in there.

If you're really an FT'er...

For hotel and car, see if you can get away with booking as many split reservertations as possible. If you don't mind returning a car every day (say, if the hotel has a rental station), on Hertz you'd be mid-tier in 2 weeks, and top-tier in 8 weeks. If you don't mind moving every night, you can accumulate huge stay-counts by mattress-hopping.

Also, once you know your car and hotel alliance, visit the forums on FT. For instance, with ICH, seem to remember there's a thread about combining/mixing promotions, to get monster points on combos.