ISS is actionally falling towards the earth and therefor they don't feel gravity. But ISS is falling in a direction towards the earth. So the astronauts living in ISS probably live in ISS in a manner which would be directed how ISS is organised. All the instruments are probably easier to work with when you are up (at the 'ceiling') or down. Perhaps also the beds have a preferred site, but I don't know for sure. So is there is preferrenced site or does is it really not mater?
ISS does have a sort of 'up and down', deliberately created as part of the design. All the modules apparently have a consistent 'up' orientation in one direction. The majority of lights are in the 'ceiling' and are set up to shine 'downward'. Furthermore, all the writing on the walls is pointed in the same direction, so that it is 'right side up' in relation to the 'floor' and 'ceiling'.
I can think of one place where you would prefer to have your head in a specific direction.
The nadir (Earth facing, or "down") Cupola module is a popular place among the cosmonauts, where you can look down at the Earth. Here, you want to stand in such a way that your head is able to watch out of the windows.
Beds do not have a preferred direction, in fact, the sleeping compartments are stacked in a square around the node-2 module in the American segment.