Our habit is one longer drama and one shorter light subject. So far we have done:
Adventures of Brisco County Jr
Life on Mars (UK)
Doctor Who (9 and 10)
ETA: Forgot Worst Jobs in History, fun Channel 4 Tony Robinson quasi-doc
I favor shows with likeable characters; I can forgive much else if I enjoy hanging with the people. It's nice if they avoid idiot plotting, and we don't have a lot of patience with the mediocre; the last seasons of Red Dwarf and Veronica Mars and the first season of Blackadder all got the hook due to quality issues. Heroes and Supernatural are right out, because hot men do not balance out racial and gender skank for me, and zdashamber is not a fan of Lost.
We are starting to consider nonfiction shows, old shows are just fine (note the Brisco County in that list), and anime is okay with me though I don't know if tersa and zdashamber are fans. I'm thinking of suggesting Ashes to Ashes, since we enjoyed Life on Mars, and Alton Brown's Feasting on Asphalt series and The Tick cartoon has come up. What else do people want to toss up as suggestions? I've heard good murmurs about Leverage, and Merlin enjoyed a brief vogue on my friends list a few months back (though there seemed to be somewhat of a "silly show, but fun" vibe.)
Pimp your show! Feel free to link this post to other people, if you want them to pimp shows too.
(temporary TV icon enabled, but I'll come up with something else later)