I find that I use the ATH-ESW9 more than any of my other headphones. Even though I often listen to music in bed, I'll lay on my back with the ESW9 rather than on my side with the ATH-CK7 as I normally would.
The ESW9 is simply a stunning headphone and it is hard to imagine a classier design. They were a bit clampy when I bought them but the grew more comfortable very quickly. Some people (including me at first) have a hard time justifying the purchase ($275 USD for me) but they sound so much better than any other headphones I've heard in the past that my constantly nagging feeling that I need to upgrade has been quenched. The consensus on head-fi.org seems to be that they are the best closed portable headphone on the market and from my experience I am inclined to agree. Whether they are worth more than twice the price of the ATH-ES7 is a matter of personal opinion. The ESW9 certainly sounds much much better than the ES7 but the ES7 is a competent portable headphone and is waaaay cheaper at about $110 USD. I'll get to sound soon but as a matter of comfort the ESW9 easily beats the ES7 which is much clampier. The ESW9's lambskin earpads are a huge improvement over the pleather pads on the ES7 since they are more plush and less sweat inducing. The ESW9 also looks better on the head than the ES7 since the headband does not stick out at a funny angle. (This can be fixed on the ES7 as can be seen here. (Thanks 3X0) The ES7 also can get scuffed very easily in day-to-day use. They are both very solidly built and can easily stand portable use. They both come with carrying pouches and are both made in Japan. I don't have it yet but I think I'm going to buy this case for my ESW9 so I can toss them into my knapsack.
Alright. I've got to go so I'll save my sound impressions for later. (They are amazing ;) )