If one or more rooms will ever have personal use and/or be converted back to personal (while the others are still rented), I would keep it as three different properties with three different Schedule E worksheets.

If they will all be 100% rental for the long term, or if they are converted to personal use they ALL will be converted to personal use, I would put everything on one Schedule E worksheet.

As for depreciation:  In the first situation above, use three different worksheets.  The "placed in service" date is when it was first AVAILABLE for rental.

In the second situation above:  If the rooms were AVAILABLE at different times, technically you should do three different worksheets.  However, due to the very minor difference, I suspect I would just lump it all onto one worksheet.  CAGMC.