aw piano music's all right! i agree with Waldszenen- balancing with a variety of chamber, orchestral, choral, etc. music. really depends on the mood you're in, but i love listening to piano music. but hey i love listening to renaissance choral works that others apparently find boring or depressing- how can you think that, it's lovely!
i did go through a phase last year when i didn't really like listening to piano music, but moved out of it when i actually listened to it properly rather than playing it as background music whilst doing work