The reception area looks just a bit too luxurious for a
warehouse. It makes me think that the warehouse must be run by
the mafia or some major crime organization (pimp daddies).
I found this photo of a real warehouse stairs and loading area, so you can have some additional ideas.
http://www.cls.usask.ca/images/Site/Phot.20010622/handrails%20and%20stairs%201.jpg
The frame for the glass windows appear too thin and recessed to be
realistic. Consider making them wider and maybe even with another
texture.