The State of Things is one one of my favorite shows on WUNC, so glad to hear Frank & co. talking sci-fi movies.
A bunch of great movies get mentioned, but if I had to add one, probably go with Children of Men.
My flickchart is subject to radical change at any time ... but you can see the current rankings of my favorite sci-fi movies over there.
Side note: I had no idea John Kessel (who phoned in to the show) teaches at NC State. I've got a signed copy of Good News From Outer Space on my bookshelf that I picked up when I met him, Kim Stanley Robinson, and Lucius Shepard at a signing at Ziesing's in Willimantic, CT back in 1989. I still shake my head in wonder at how lucky I was to meet that much talent in a tiny bookstore.