I've never had my interest in something evaporate so quickly as 24
after it ended. Fox was smart when they began scheduling it in uninterrupted season blocks in the fourth year. Even when the show went of the rails, that provided enough inertia to keep me coming back.
Now, though? I can barely remember the cliffhanger the series ended on (and why did they end it on a cliffhanger again, when they knew it would be cancelled?). Meh.