I cannot wait to go back and try again! We are leading a workshop to Eastern State Penitentiary on Sept 21st and we will have the entire place to ourselves before the public arrives.
I took 9 different compositions each of 7 exposures images from the hallway (without moving my tripod feet I took 3 compositions (7 exposures each) looking left left, another 3 looking right and one head on); all at 17mm with my back against the wall. I also took 2 compositions (of 7 exposures) each looking inside (21mm) with my tripod at the doorway.
I HDRed the 9 sets of 7 images into 9 images and then merged them into one. Cool, but you really cannot see inside very well.
Then I layer masked this (14 image) composite into the doorway.
Then I applied Nik midnight and detail extractor.
If you are not versed in HDR capture and processing you could just take 9 images (instead of 63) and photomerge them into one panorma. You would not have detail in the shadows and highlights.