Firefly... I think the only series on DVD that I've actually set asside for more than one complete viewing, but there are a lot of series that I've watched through once, but would be willing to watch through again. The Wire, Deadwood, Rome, Treme (yeah, I know it's stil on, but I'd restart from first season, if asked to)... eventually Game of Thrones. (Yeah, HBO kinda kicks *ss when it comes to good, complex writing and replayability.)
Studio 60 on the Sunset Strip... Bought it for a song via an Amazon Gold Box deal. Haven't had a chance to re-watch more than a few episodes, though. (Ma-in-Law was in chemo, and her befuddled brain couldn't keep up through a single scene, let alone an entire episode.)
Movies I can't channel surf past:
PCU - I know in my very bones that it's not as good as I once thought it was, but we're talking about George Clinton jamming a house party. Not much that can beat that, except...
Animal House - ...Otis Day and the Knights jamming a house party.
Ferris Beuller's Day Off - We own it. I can see the DVD from here. If I pass it playing on TNT or some other cable channel, I'll still stop and watch. This movie helped define my highschool and college years... and I wasn't even IN highschool when I first saw it.