Hey C,Boiler rooms and catacombs aren't really "themes". They are more like "settings" or "ideas for set design", but they aren't "themes". And that's fine if that is the beginning of your inspiration, or perhaps part of the "motif" you wish to capture, but eventually in the design process you are going to need to nail down a theme in terms of what you guys will be doing; or two, as the case may be, if you are doing two separate houses.
A theme is a specific genre or sub-genre which helps you make key design decisions early in the process, and gives the audience a context in which to work, in terms of what to expect.
For instance, what kinds of monsters do you want to live in the world you create? What happened in this space? What's it's backstory? Stephen King once said that a place can't be haunted unless it has a history. What is the history of this place?
If you want to have boiler rooms, warehouse basements, and cavernous catacombs, that's great, but what's happening in them? Any number of themes could include all those design elements, but what's the story?
For instance . . .
- Insane Asylum: on the upper floors, everything looks proper and probably passes state inspection on a regular basis, but in the basement and/or lower levels, terrible experiments take place (ref: Arkham Asylum from Batman Begins).
- Hospital: like above, only in this scenario, in a hospital that specializes in body part transplants, the doctors get an unlimited supply of body parts from the undead bodies of catatonic demons who are buried in the catacombs below.
- Circus: when not traveling, this demon circus hibernates in catacombs beneath a warehouse, accessible only thru secret passages in the basement. The circus equipment is stored in the warehouse.
- Were-beasts: an evil corporation is developing a serum to turn humans into were-beasts for a military contract to breed super-warriors. This happens in the secret labs in the basement of the corporate headquarters, or perhaps a remote warehouse location.
- Zombie Apocalypse: in this setting, it practically writes itself.
- Alien Invasion: either a) the last humans on Earth are trying to survive by hiding in deep catacombs, or b) the catacombs are actually hives the aliens created (ref: James Cameron's Aliens).
- Victorian Manor: interesting opportunity to try out some steampunk ideas (given the boiler room setting, and whatnot; ref: Guy Ritchie's Sherlock Holmes series).
Those are actual themes, and ways that they can work with set ideas such as a warehouse basement, boiler room, cavern, or catacomb setting. I'd hesitate to call those set ideas "motifs", because usually a "motif" is much more operative or causal in the design process.
Also, another critical thing is that whatever theme you choose should have naturally occurring fears or phobias built into it, vs. something that you have to go out of your way to manufacture, fear or phobia-wise. For instance, vampires aren't terribly scary these days and don't make for a really good theme because they don't tap into any naturally occurring fears, beyond perhaps xenophobia or "the fear of strangers" (which, incidentally, zombies own, hands down . . . that's the driving fear behind zombies).
Now, vampires can make a great "motif", and would work wonderfully with any of those themes listed above, but without a driving fear being incorporated into the overall production, you will be fighting an uphill battle. Remember, vampires are hot, and popular, but for all the wrong reasons as far as we are concerned. Thanks to Stephenie Meyer, vampires are no longer evil blood-sucking demons who steal innocent, sleeping newborns in the dead of the night to feed to their hellspawn succubus brides as a midnight snack. Instead , they are gorgeous, pouty lipped male models with glittering skin who are hopelessly romantic and eternally devoted to their human soulmates. The only fear I see them generating these days is in the boyfriends of the girls who attend your haunt that the their girlfriends will want to trade-up.
All of those listed themes have built in fears or phobias, or potentially frightening scenarios that lend themselves very easily to them.
WOOOW! Love the details...that'll help us finalize our "Themes". Appreciate the time & thought you put into that reply. We're working on a "history" or "story line" and work our settings around those. Thanks again.