I tend to go for crime dramas, good sci-fi (of which there are very very few, imo), history, science, nature and home improvement (the construction/building side, not the furniture purchase/decoration side).
I don't tend to keep up with many shows on a week to week basis too often, partly because I just forget. Don't like planning my schedule around TV. But I'll catch up on shows via our cable On-Demand service sometimes.
Currently the shows I tend to watch most regularly are:
Walking Dead
Big Bang Theory
The Voice
Full Metal Jousting (surprisingly watchable)
Pawn Stars
American Pickers
Holmes on Homes (he cracks me up)
Face-Off (I like special effects stuff)
The River (not great, but I watch for Bruce Greenwood

)
Mentalist - loved it initially, but kinda stopped watching. Once in a while.
CSI:Vegas - occasionally (degraded after Season5 or so and when Grissom left I stopped watching for a year. Ted Danson is ok)
House (after 4th season I only watch sporadically now)
Sherlock (the British one set in modern day) - awesome stuff, wish it was longer, and I can't see the 2nd season yet).
There's no sci-fi/horror/fantasy serial on US TV that I currently like. Tried the USA Being Human recently but meh.
...that's about it for serial TV.