Headphone I can stand for more than 1 hour

I have the Senn 590's and they are very light and comfortable. I've read several other threads which indicate the 570/590's are more comfortable then the 580/600's line, but I only had the 600's on for a short demo, so I can't really comment more then saying that they did seem a little heavier IMO.

Gee I kinda like my Stax Pro Lambna's, cost me $700 back in '90 and still going strong, I could never go back to dynamic type headphone the electrostatic is too revealing. They are big but not uncomfortable. Stax dedicated headphone tube amp is a must.. improvement over their voltage conversion boxes. Model 007t or something like that is what I use, sounds great.

The most comfortable phones that I have are: Sony R-10, Sony CD3000, Stax Omega II, Beyerdynamics DT-880, DT-770 Pro, DT-990 Pro, Sennheiser HD-600, Audio Technica W-100. I totally agree that the AKG K-1000s put a lot of pressure on your temple, as do most Grado headphones. Other than the Sony R-10's and Stax Omega II's, all of the other cans mentioned above are reasonably priced (from under $200 to $400 range) and widely available.

Beyerdynamic DT880 and AKG K501 should be all right for a long listening.
Certainly more comfortable than SR225.
Grado's RS1 is not as bad as the rest.

I'm a stax man. I have owned the Gamma and the lambda and they are comfortable and have the sound I crave.