Just listen to whatever you like. I listen to everything. Some days I like to listen to a good oldie, like Led Zeppelin or The Who. Some days its the 80s. Some days I am feeling mad and frustrated and I need to listen to hardcore, some downset, perhaps Sick of it all. My roots will always be in punk though. Sometimes I get in a different music style kick, but it always comes back to punk. face to face, NOFX, NUFAN, Lagwagon- it always comes back. It just makes you feel goooood.
I don't own anything besides punk, for the most part. I Love the bands mentioned by bally, and I'd like to add a couple--Strung Out, Good Riddance, Less Than Jake, BR, Ignite, HB, Madball. I recently started listening to some more main stream stuff such as Incubus, because they have such good bass lines, and stuff. Oh, I absolutely LOVE Cat Stevens, I remember listening to that when I was young, and I never got sick of it. Great stuff...great stuff.
i like all that stuff too, but i'd like to add a few: Raffi, ethyl mermon, yanni, kenny g, and of course wally pleasant