After a bunch of research a few years ago, I ended up buying a pair of the Denon AH-D1001's mentioned above, and I'm thrilled with them, though my use case is a bit different than yours.
I have them plugged into my Mac at work, and I was looking for accurate, unfatiguing sound, comfortable to wear all day, and not leaking sound into the (office) environment (which would rule out the otherwise impressive Grado's).
(FWIW, the Denons retail for $149, but I was able to find get them for a bit under $100 with a bit of patience and googling; at the moment I see OneCall listing the Denon AH-D1000S -- which is the previous model, but no real difference -- on Amazon for $99 with free shipping.)
A few of my friends swear by the Sennheiser HD-280's for the much the same use as I'm doing (and the price is nice), and I found them to have very good sound, and great isolation from outside noise, but they clamped my head so tightly I was worried about getting headaches (thus failing the "comfortable to wear all day" test) -- I've seen more than one comment about keeping them opened around something like a basketball for a few days, initially, to "stretch them out", so they don't squeeze your head so much. Sennheiser makes quite a few headphones with terrific sound in (mostly) price ranges above what you want to pay, which I steered clear of because they're (mostly) "open air" designs, and leak lots of sound into the environment ("your friends and neighbors can listen along with you"), which was a deal-breaker for me, but may be fine for you.
I would recommend looking around both on the
http://www.head-fi.org/ web forums (which fits in the "taking a drink from a firehose" category) and
http://www.headphone.com/ (which sells headphones, but has some very nicely done reviews, and lists of "best headphones for use X, and why").