Here's your short list:
KSC-75's. You should get these, period. You can still get some "full size" cans, but as one of the previous posters alluded to, these are easy to put on, they are cheap, you can put them in your pocket if you want to be more active, I mean, seriously, for $10-15, there is no reason you shouldn't get them. I have like 6 pair. And I have to believe they sound far better than the skull buds... They are open, and will leak noise in and out, but I find them less bothersome than grado's from that standpoint, and when I'm out and about, I do like to hear what's going on around me, so that's a plus for me.
Portapro's. Similar/same drivers as the ksc-75, but with an adjustable and folding headband. Not as portable or disposable as the 75's, but probably more comfortable for longer sessions and you could wear them around your neck. Cost more (at least $30-45)
Grado's. I love grado's, but they leak music out too much to be used around others all day. They would probably also present comfort issues for all day/every day wearing. Although I've never broken any, they do have a lot of small moving parts which could conceivably break fairly easy if you snagged the cord or something. Speaking of cable, the stock cable is not made for portable use, way too long and stiff
Denon d1001. These would be the ones I would buy along with the KSC-75's for your use and tastes. Great headphones, you can pick them up for $75 to 100, nice short flexible cable that is great for portable use, leak very little, but don't isolate completely letting you stay partially in touch with the outside world, comfortable for long periods of time, don't need an amp, fun sound with your preferred genres, size is compatable with portable use (not too big or ugly) I've tried nearly everything in this price range (seriously) and based on your checklist, I really believe this is what you're looking for.
ES7. These are the only ones I haven't tried and are often compared to the d1001's. I plan to pick up some of the refurbs that are going for $60-80 so I can compare them to the others I've tried.
JVC RX700/900. I think these are too big/bulky for daily portable type use and the cable is WAAYY too long. I've tried them for this type thing before, trust me, the d1001 is worth the price difference. Good for the price, but not for your application.
IEMs. These, to me are also a hassle to insert, not comfortable for long use (unless you shell out $1000 for customs), and scary to use out and about because you are completely cut off from the outside world. I think you would be disappointed.
AD700. Someone may suggest these as great headphones in your pricerange, which they are, but not for what you want. Way too big, cable is way too long, they are way too open, and they aren't as much fun for the music you like to listen to. They are great for like an office or home listening because of their detail and comfort. Not for you.
I have to go, but I could talk about several others. My suggestion is Denon D1001's PLUS the KSC-75's. You'll thank me.
JJ