Personally, I post virtually everything I want to talk about in the Salk circle, and I comment when I can on the AVA circle (as I own their gear as well). Simply because I'm not going to look through 100 circles to see what topics are relevant to me, and quite frankly, I enjoy the familiar groups of people on these 2 circles (where I have spent considerable time the last year or so). I've only recently dabbled in the Classical circle.
I've found that considerable time, effort, and money has been spent on just the Salk circle members alone, that I can get an informed opinion on virtually any audio topic that would be important to me. I would assume that others who have similar time invested in other Circles feel the same.
But on topic, I find the Up Blu - Ray to be particularly excellent, and AVSforum rates it a reference quality as well as the recent Blu Ray release of Monsters Inc. I can't comment directly on concert blu rays, because I don't have any. I think the best combination of sound and video showmanship may be The Incredibles and to a lesser extent, Finding Nemo. Both are very vibrant with color and have fast motion scenes, and the Incredibles has an amazing soundtrack as well as some very crazy subwoofer scenes. Finding Nemo is delicious looking and has one of the best sub scenes around, but I don't find the soundtrack particularly engaging. The only concert DVDs I own are Dave Matthews Concert In Central Park, and the two Ben Folds DVDs (WASO in Perth, Sessions @54th). Sessions @ 54th is amazing even though it is not on blu ray.