I've heard QuietRock in action, and it's pretty impressive. The company publishes STC ratings which back up their claims.
See: QuietRock Soundproof Drywall
The big downside is that it's really, really expensive.
Also, as far as getting on "speaking terms" with my upstairs neighbors, it's pointless. For one thing, I can easily hear even "normal" levels of conversation. So even if they decided to not be jerks, I would still hear everything.
These people have a party until 4am nearly every weekend. When I call to complain at 4am, they act surprised. Every. Single. Time. They do it to spite me now.
My only other option is to have them evicted. I own 38% of the building, so just need one other unit owner to agree, and their lease can't be renewed. If I can't come up with another solution, that's what will have to happen.
But, as I said, even if that happens, if somebody new moves in, it will still be loud.