Rob and J Mac -- thanks for getting the thread started and keeping it alive. I made my first attempts at some Brenizer panos recently and while it was mainly a learning exercise in the negative sense (what not to do), I'd like to join in. I attempted four different panos in one outing, using a Pentax-A 50/1.2. My first was ineffective, because I was too far from the focus plane, so that the background wasn't blurred enough to still look really blurry when the pano is scaled down to reasonable size. So I learned that you need to be close enough to the subject to get a strongly blurred background.
My second attempt I managed to defocus the lens early on, so that nothing is in focus. Oops. So I learned that I am an idiot, and also not to rush.
Third attempt a little better:
I'm still a little too far from the focus point, so that at this small size the background doesn't look all that blurred, but there is at least some of the effect.
Fourth attempt less effective:
Even though I'm closer to the focus point, I think the reasons the effect doesn't quite come across (at this scale; works a little better when larger) are that I didn't include enough blurry foreground, and the subject (the sculpture) isn't isolated enough to stand out.
So, next time I attempt this, I'll look for a subject that is isolated from its immediate surroundings, well lit to help it stand out, get fairly close to it, and include plenty of foreground as well as background.
Also, I think it's important to choose a subject whose scale is easily discerned. That's one reason people work well for these. But also why Rob's park bench and lawn mower and J Mac's horse work well.