I only watch two network shows; '24' is one, 'Smallville' the other. I would agree...for television, '24' is the closest you'll come to an 'edge of your seat' storyline.
Smallville is okay. They did a good job recasting the Superman mythos, and the evolution of Lex is interesting, but the rest is pretty weak. It's slipped down to my occasionally watchable list . . .