Soundproofing a Semi-Detached

Has anyone ever soundproofed their semi-detached house, or a shared wall in your home?

We are in the process of buying our 60s era semi-detached.  Our neighbours on the other side are fairly old, but have got young grandchildren who come over early on the weekends (when we catch up on sleep).  Conversely, we go to bed very late during the week, and I'm sure they're already in bed by the time we go up to our bedroom.

The walls we share are on the livingroom/master bedroom/second bedroom side, which I really hate.  I would much rather share a hallway/stairway/bathroom wall with them instead...makes no sense to me.

Anyway-- I have no idea what the walls are like construction-wise.  While the sound isn't a MASSIVE problem for us right now, other than a bit of guilt when we're banging things around late at night, I hesitate to think how much the neighbours will appreciate things like barking dogs and crying babies when our family grows.

Has anyone had any success with at least lessening sound from the other side of the wall?

I wish we had done this when we refurbished our 30s semi.  Our neighbors have five kids and the mother's voice sounds like a yetti.  I talked to a builder and it's doable - they use the same stuff that they use in recording studios.  He said that they normally suggest just doing the main living area and perhaps one or two bedrooms as it can be expensive...it means you have to replaster along with adding the soundproofing.

Have you tried putting wardrobes and/or floor-to-ceiling bookshelves against the shared walls?

I'm not  sure that there would be any appreciable benefit compared to the outlay/mess. Fact is that the physical connection is the big problem and once your mind is focussed on the sound,its amazing how much more annoying it is.

I'm also in a semi-detached house with OAP's next door.  It seems to work to our benefit though since they are fairly deaf and don't seem at all bothered by our crying babies.