Most classic rock - late 60's through the 70's: CSNY, Pink Floyd, Journey, Zepplin, soo many others.
And a lot of what would probably be considered today as country - Eagles, James Taylor, etc... That stuff is always good.
New favorites include bluegrass/newgrass (Allison Krauss & Union Station, Bela Fleck, Sam Bush - and a local band called Runaway Planet - they put on a great show live (they have a website if anyone's interested -www.runawayplanet.net). I also love listening to Nora Jones. What a talent.
Actually, I love all kinds of music - I appreciate musical talent, even when I don't necessarily like the particular type of music that's being played. My nephew is one hell of a drummer - and plays what might be considered alternative rock (I never can understand a word the lead singer says

), but I even enjoy listening to him, because he's so good at what he does.
When I play (I play acoustic guitar - have a Fender Resonator), I mostly like to play music from the second and third categories above.
K