I know you're looking at the higher end of the sub-$300 cans, but I strongly recommend the Sennheiser HD238 under the following circumstances:
- to be used indoors b/c they're open cans (which seems to fit your need)
- you're okay with on-ear
The sound is pretty detailed with punchy bass and nice mids and highs - I like em much better than my HD280s. You can find deals on them on amazon or ebay for less than $100. They have a low impedance so drive just fine on ipod and such too.
They're very light, and the pads sit right on your ear but don't add much pressure. My hat size is around 7 3/8 if that helps at all.