I'm new to Pandora as of Feb 2009 - so my bookmarks aren't fleshed out yet.
Grew up on the Johnny Cash/Charlie Pride/Marty Robbins/Hank Williams kind of country music that my parents listened to.
Migrated to rock/pop in high school with a smattering of classical (William Tell Overture) and show (Cole Porter) from school band. In late high school a TV series called "Nostalgia Theater" introduced me to big band through movies from the 30s and 40s.
College expanded my listening to jazz, folk and more classical. Since then I've wandered around. Working in jazz and classical format radio stations segued to greater interest in those styles leavened by a growing interest in blues.
Somehow I bumped into and really liked Steve Reich, Terry Reily and their ilk.
Don't listen to much pop anymore. Taking up clarinet has intensified an interest in "trad" and Dixie jazz while exposing me to the kinds of things that band leaders of the Sousa era (it ain't all march music) would have presented.
My wife leads me to more world music and pre-bop jazz as seen through the show filter.
I do have a few dislikes. Opera, recorded reggae, and accordion music of the Lawrence Welk/Myron Florin school.
Mostly it's "if the ambient mood fits, listen.