I listen to music nearly all day at work. It's actually something I love most about my job. For about 3 weeks now I've been using my new Harman Kardon CL on-ear headphones. And I'm in love.
Th CLs aren't cheap. They'll run you $199 at The Apple Store (one of the few authorized retailers), but if you listen or enjoy music as much as I do, they're worth every penny. They also feel the quality if the price- metal headband, comfy memory foam ear pads and 2 sizes of headbands that form to your dome.
I've never really owned a nice set of headphones before, and if $200 headphones aren't worth blinking at, then you may know different. For me, the sound on these are amazing. I now want to ensure I'm listening to quality audio files so I can hear those nuances I've never heard previously. The CLs aren't bass heavy, but you'll get a fantastic low end. The highs are crisp, and everything in between sounds great to me– again, purely based on my previous experience. Sound isolation, even for on-ear headphones are really great, thanks to the memory foam.
My only complaint here is that I wouldn't take them with me on my commute. The just feel like indoor headphones and I wouldn't want them to accidentally get dinged or rained on. So they stay at the office. However, If I take a plane, I'd most definitely bring these along.
Overall? If you got about $200, don't have Bowers & Wilkins P5s (though, they compete with the P3s) or some other fancy high-end headphones, you will not be disappointed. In fact, you'll want to thank me. You may do so in the comments.