My living situation is about to change and I likely won't be able to have a 2.1 reference monitor setup for an extended period, but I'm starting a new album. So, I'm looking for headphone recommendations. I'll be using them both to compose/program and to mix. I'd probably take it to a friend's studio to 'master'. Anyway, the cans must be:
 

• Under $200
• Over-ear (important, I wear glasses and headphones that rest on the ears hurt after a while)
• Reasonably accurate response across the full range. No hype and no significant loss of low end.

Thanks in advance for any advice you can give me. Really looking for headphones you have actual real-world experience with. Please no 'you shouldn't mix in headphones'. I know that already. I won't have any other option for a while.

I've used Audio Technica's 'ATH' range for a long time now, currently using the 'Air ATH300's, which I think cost around £50 ($80). I find them very comfortable and use them for mixing and listening to music/watching movies in the studio. If I was going to upgrade I'd probably go for the ATH-M40-X, which are around £80/$150.

The ones I have experience with are the Beyerdynamic DT 880 headphones. Large, very comfortable over-the-ear cans. If they weren't $280, I'd give you some links. I own a couple of other headphones that were less expensive, like Sennheiser HD 280 Pro. They have good sound (more for listening that mixing, IMO), but are not comfortable for extended periods. I haven't used Audio Technica, but a pair of ATH m-50x mixing headphones @ $169 from Sweetwater are on my wish list. Given the AT thumbs-up from jamesg1213, that would seem like a good direction to go. I just love my DT 880s and had to put in a plug for them. 
 
Edit: As an aside, from your usage description (not recording live vocals over a backing track), semi-open or open headphones might be more suitable, from an extended-wear perspective. The DT 880s are semi-open. I don't ear-sweat in them, like I do in the HD 280 Pros.

I was going to suggest the pair I currently have (Ultrasone 750), but the price has significantly jumped up quite since I initially bought them for ~ $200. I've been using this for the past 3 years in recording/mixing, and do find them to be very accurate with excellent spatial separation.
 
In case you may like to read up on it, here's an SOS article: http://www.soundonsound.com/sos/sep11/articles/ultrasone-pro-750.htm 

I use the Audio Technica ATH M50 and they're superb. Over the ear, very comfortable in long runs. I wear glasses too. Sonically excellent.

Sir William
I use the Audio Technica ATH M50 and they're superb. Over the ear, very comfortable in long runs. I wear glasses too. Sonically excellent.

Quotes like that are the reason those phones are on my wish list! 

I've been using KRK's KNS-8400 for years and love them... Sonarworks headphone calibration software has profiled the 8400's.  There's  pretty much universal agreement this improves the quality of hp mastering...  

TheMaartian

Sir William
I use the Audio Technica ATH M50 and they're superb. Over the ear, very comfortable in long runs. I wear glasses too. Sonically excellent.

Quotes like that are the reason those phones are on my wish list! 

I use them at the DAW almost exclusively while tracking and mixing. 
 
Then I move to Senheiser IE6 (buds ~$100 just bought my second pair for $69) for verification.
 
I have others too but they are out of your price range.

Audio Technica ATH-M50x

 
http://www.innerfidelity....0x#FWzhjb2z1CP4xUe6.97

Vastman
I've been using KRK's KNS-8400 for years and love them... Sonarworks headphone calibration software has profiled the 8400's.  There's  pretty much universal agreement this improves the quality of hp mastering...  

I should add that I also use the Sonarworks Headphone Calibration software for my ATH M50.

Plus, I also use the ATH IM70 inears to mix occasionally and find the same calibration setting works great there too.