My mainstay is classical music - if I'm studying, relaxing, or reading, I can always turn to a classical music station and be quite happy. But I don't really listen to it that much, because I have so many other exciting things to play!
One thing that I enjoy a lot is Christian contemporary music. I don't tend to listen to a lot of it, though; I've singled out two groups in particular that I like more than the rest: 4Him and Acapella (a division of The Acapella Company). 4Him is a really energetic group with a very pleasing sound, and Acapella is just neat to listen to - they're extraordinarily talented.
For a change of pace - a very BIG change of pace - I listen to They Might Be Giants. I've finally heard all of their CDs, and each one reinforces how much I love this group. Not only do they keep their songs decent, but they're hilarious and clever at the same time. (My favorite album is still Flood, though!)
Another band I've decided I really like (thanks to "Buffy") is k's Choice. Happy songs plus a very nice sound equals good.
Around Christmastime, I get a hankering to play Mannheim Steamroller all day. They remix traditional Christmas tunes and revitalize them. I've heard the traditional versions of some songs after listening to Mannheim Steamroller's incredible versions, and they seem so dull!
A more recently-developed taste of mine is folk music, mainly Celtic and Russian. I particularly like the Irish groups Clannad and Enya, the Scottish Battlefield Band, as well as Welsh music. (Welsh folk is rather hard to find, but Past Times in the UK sells a very nice CD with lots of good songs.) I also really like the Cuban singer Silvio Rodríguez (esta página está en español).
Now, if I may, I'd like to ramble on a bit about Battlefield Band. I had the thrilling opportunity of seeing them in concert in Lewisburg, West Virginia, and I'm very impressed. While the concert itself was wonderful and their music was as enjoyable as always, the highlight was getting to visit with band members before and after the concert, and during intermission. John McCusker was setting out CDs when we arrived (an hour early, accidentally!) and he was quite happy to talk with us as he worked. Later, he signed a few autographs and posed with us for a picture, and greeted us with a smile whenever he saw us again throughout the evening. Many thanks to John for making the concert especially memorable. And although we got to know John the best, the other band members were equally willing to sign an autograph and have their picture taken. It was a great time, and I encourage anyone who has the opportunity to hear them to do so!
I also love show tunes. I appreciate most the soundtracks of plays I've seen, but I've been known to thoroughly enjoy soundtracks of ones I haven't. Wuthering Heights is a great example of that (but then, it's got Bonnie Langford. Of course I like it. Even if she does only have one song...).