I've been using Sennheiser HD515's for, uh, closer to three years I think. Been good, although there is a mechanical vulnerability in the structure of the phones (it's possible for the wire connecting right speaker to the left to be mangled in repeated use, which can cause sporadic playback on right ear. Can be fixed though. Also, they are open dynamic headphones which means they don't really attenuate sounds from the environment. For that, closed headphones are better (and a lot more sweaty to use). Sennheisers are a good brand, if you have the cash to spill on them.
When I'm traveling I'm using Koss Sparkplugs. They aren't expensive, but produce sufficient audio quality and pretty good attenuation of environmental noise.