Any advice, anyone?

I'll be listening to a variety - hip hop, classical, jazz, bossa nova. Listening will be primarily on an MP3 player or laptop, either in public transit or libraries.   So with all that said, I do want headphones that actually clearly hit the bass I hear in modern hip hop, but overall sound...

I'm in the market for a fine pair of headphones on the order of $100 and have been considering the Sennheiser HD 280s and 448s, but haven't been able to find either in stores to take a listen.   Judging by the technical stats, the HD280s are superior: they offer a greater frequency response...