A few things you may not know:

• In SFUSD, teachers get three days of professional development before one work day.  This isn't enough to set up an elementary classroom, so teachers typically go back to work early (I went back on 1 August, not including the two weeks of professional development I did in June and July or some planning in both months).  However, this is unpaid labor.  Kindergarten Roundups and orientations usually take place before the work day, so do not expect to be able to visit the rooms.
• Elementary room set up means just that.  Usually all the furniture is taken out for floor cleaning, which typically requires the contents of shelves be boxed up and everything be removed from the floor.  Some schools wash the walls too.  So no matter how cute and little your child's teacher may look, s/he is a furniture moving expert with the muscles and bruises to show for it.
• If your child's class has pets, your child's teacher had pets this summer.
• The moral of the story is: If you appreciate your child's awesome, polished, inviting room, think kindly on the hard labor that went into it!  Teachers want to have nice rooms - beyond everything else, we'll be living in them for the rest of the school year ourselves!  But sadly, Classroom Fairies are a myth.