i usually buy cross trainers for lifting and cardio, since i'm not running any marathons, a hybrid is good enough.
a lot of hardcore lifters like converse 'chucks' for deadlifts and squats. they are very flat footed, unlike tennis shoes which often are thicker in the heel.
i've lifted in my airwalks a few times doing squats and kinda liked it, but they suck for running, period.