Hey wonder,
+1 on the UE4000s, except that they don't fold. They are very compact already, though... Other than that they seem perfect for your criteria.
If not, you could go for the Monster DNAs. I tried them at the Apple Store for about 20 mins and came away pretty impressed - they are supraaural, they fold up nicely, they are comfortable and they actually sound pretty good. The bright blue/cyan wasn't quite to my taste, but they have other colours.
The DNAs have a moderate bass emphasis, which helps with the isolation (I think they isolate quite well, by the way), and also sports pretty decent mids. The highs are not piercing - in fact, they're not very 'present' relative to the mids and lows. I think the DNAs would be great for you, but they'll need you to stretch your budget a little bit (I'm sure you can find them on sale, their MSRP is 199). Good luck.