Just a point, there are TF companies with NSAI certification that do closed panels sytems and alternatives to the standard block outer leaf. On sound, this is a tricky one, because it is very much depends on the occupants so whats a good solution for one person may not suffice for another.... but i would agree that a concrete screed to the first floor works v well (to my ears at least)
p.s. before anyone asks, i do work for a TF company.. i came across this when i googled something else.