At the risk of stating the obvious, putting a decent underlay and carpet is probably the easiest/cheapest.
I am sure there are more sophisticated solutions, but there would have to be achieved either by lifting the floorboards and filling between the joists with some sort of insulator and/or putting an additional ceiling on downstairs rooms.
I don't understand what the eves have to do with it? If it is a dormer bungalow then the eves are the storage space with a low sloping ceiling right? I doubt there is much happening in there for any great length of time.
Also, I thought you weren't supposed to put insulation in between the joists in the flooring/ceiling?
Perhaps just put some nice rugs in the rooms to stop most of the noise?