When I was still living in the college dorms, I liked to change the layout of the room once in a while. It was a hassle to move the furniture into a spot and having it end up not working or just not liking the new layout.
What did I do to solve this problem?
I went to the housing office and asked for the floor plan to the building, measured the dimensions of spots in the room to make sure they match the dimensions on the plan and went from there. I made quick models of the furniture we had in each room and placed them where they needed to go. Of course I didn't model all of our furniture, just the things we moved often.
Whenever we wanted to move the furniture again I'd just load up the file and start moving things around. I probably should have been working on another project at the time but this was worth it.