Honestly I'm less worried about the price between these three - ie not worried about bang for buck but best sonically.  Do a lot of people prefer the HD600 to the HD650?  Also, I'm getting the impression that either of those Senns is preferred over the HE-500 by many or most?

Not simple questions, I will try to be brief.

As between the 600 and 650, there is endless debate and only your personal preference will tell you what is best. That said, hans listened to and measured both, and was able to VERY easily modify the 600 to measure and sound (to him) pretty close to the 650. Unclear if any mod trick would work that other way around (650 to 600 sound). He ended up preferring the 650, so he ditched the 600. I like the 600 for what it does, and find it a very good reference point when listening to other headphones, but the same could be said about the 650 for many. Both InnerFidelity and a thread here about the (non-) obsolescence of the HD600 extol its virtues, but again, that shouldn't really end the inquiry.

The HE500 and HD6x0 is a less simple comparison especially given the rather different bass reproduction between the Senn and the 500. Orthos generally move more air down there, but that is a very general statement, and moar is not always bettar; if you like the bass reproduction coming from the HE-400, I would guess you would find the same from the HE-500 to be anemic. Between the HE500 and the HD600, all I can say is that I sold my 500, and plan to not sell my 600 anytime in the foreseeable future (I haven't owned them at the same time to compare).

My advice (because I wish I had taken it years ago) if you are just getting into higher-fi headphones as you state in the intro thread, is saunter up to the best deal you can get for either of the Sennheisers. They are a great waypoint for very good, fullsized, open-back headphones, and perform at or above their grade depending on how much you pay.

Need some opinions/recommendations for a good pair of Bluetooth/Wireless headphones.

List of preferences (in descending order):
Comfort
Isolation/Leakage
Durability/Longevity (this includes battery life)
Sound

They don't need to sound great, just decent since it will be a gift for someone that has pretty much only used iBuds. Comfort and noise isolation/leakage is a must. It will be used mainly in the office and while traveling (train/plane). Budget is around $200.

Thanks!

Need some opinions/recommendations for a good pair of Bluetooth/Wireless headphones.

List of preferences (in descending order):
Comfort
Isolation/Leakage
Durability/Longevity (this includes battery life)
Sound

They don't need to sound great, just decent since it will be a gift for someone that has pretty much only used iBuds. Comfort and noise isolation/leakage is a must. It will be used mainly in the office and while traveling (train/plane). Budget is around $200.

Thanks!

Meelectronics Air-fi Matrix2 AF62

I picked up the Meelectronics and they are quite good sounding. They are also really comfortable - if the person you're shopping for doesn't have large ears. Their ear cup size falls into the same category as the FSP, MDR-7520, Momentum, etc.

Doctor says you got a case of the Tylls. Yessir! Gran' pappy's squishy ear, Smurf's jolly pinch.