In recent years, I've spent countless hours watching serial TV shows on DVD, devouring episode after episode. My first time watching a TV series on DVD was when I watched the first three seasons of Six Feet Under. When I ran out of discs and had to wait for -- gasp! -- new episodes to air on TV, I felt a peculiar sense of loss. I don't have a name for this, but it's a very specific feeling -- like the TV Faucet has been forcibly turned off, and you know you'll be forced to wait, like everybody else, for the next episode.
After Six Feet Under, I watched The Sopranos, Arrested Development, The Ben Stiller Show. After I ran through those I rented several seasons of The Simpsons in desperation, though I had already seen the episodes in syndication a zillion times. I started buying DVDs of shows I was already watching (notably Lost and Battlestar Galactica) and pushing those on friends. "Here, just take Season 1," I'd say. "Just have a look. If you like it, I have 49 hours more." Predictably, the addiction would take hold and I'd find a friend at my door, dying for Season 2 and beyond.
My most recent TV addiction was The Wire. Here was a series that everybody told me I would love -- and by everybody, I mean there were days when I'd see articles online about the series, I'd hear about it on the radio, then I'd get an email from a friend asking if I'd seen the latest episode. I finally gave in, and borrowed the first season from a friend. After the first episode, I wasn't convinced. But everybody seemed to love it...so I kept watching. By the fourth episode I had turned off my phone and closed the blinds, settled in for a marathon.
PopMatters has a nice Best of TV on DVD article broken up into sections -- from early "classic" TV, through "outsider influences" (read: 70's) TV, "the new networks" (read: mostly great stuff from the 90's), and finally Feasts from the Fringe (in my humble opinion, required viewing). The article gives you a great starting point for a brand new TV on DVD addiction!
So I've thrown out a bunch of suggestions above. In the comments, share your TV on DVD recommendations and commiserate about how it feels to finish a season, or an entire series! (And bonus points if you can coin a term to describe the latter...I feel like this is a recent phenomenon that flossers should have first crack at adding to the lexicon.)