Pretty much everything I listen to falls under the umbrella of hard rock/metal/punk rock, but even in that niche there are a lot of sub genres and different styles. I tend to grab a dozen or so random CDs out of my cabinet every morning to listen to throughout the day and therefore I get a decent mix of 70s rock, classic metal, thrash, hair metal, punk, etc.
...and then when I'm in the mood for something completely different I'll throw in some Weird Al Yankovic (working on a Hub about him right now!) or the "Rocky Horror Picture Show" soundtrack.
I do get on a "kick" once in awhile where I'll listen to a certain band, or a certain album, over and over again for days at a time, but it's rare.