I believe in the 2011 they tried to make it clear that residential included all the associated buildings.
Not a NEC issue but zoning and other building codes may come into play as to what you are going to call it.
NEC does not use the term "residential" they use the term "dwelling"
Large hotels and resorts most would agree are not dwellings yet can contain units that are defined in NEC as dwelling units. Now complicate it with a large mansion that is like a hotel or resort, yet is somewhat a single family dwelling.
There are manisions in Hollywood that have larger party rooms and larger parties than the community centers and auditoriums here in small town USA. Please tell me that these areas are not single family dwellings for purposes of emergency egress, fire protection, and such.
We have had for years, a local group that sponsers a "haunted house" on halloween - mostly for the kids. They usually do this in a vacant building on a low budget as the group is a community charity type of group. They can no longer do this because the fire marshal wants the building to have sprinkler system, egress lighting, ADA compliance and everything else otherwise required in other buildings. It will cost more to comply with all that then they will ever make from the gate. We are talking about groups of maybe 10 max that go through the place at a time.
I know I am starting to veer off topic... it does have some similarities - what kind of occupancy is it?