Every now and then I go trawling through exotic “dream home” sites in search of fiction fodder, and I’m rarely disappointed. There’s so much that can be used… after suitable adjustments are made.
It would be silly to put a daydream directly into one’s fiction, simply because most daydreams start out as more or less straightforward wish fulfillment. You know, having oodles of money and buying that dream house (and everyone’s dream house is different, so you can have a lot of fun discussing that one with your friends) – but that dream house on the secluded island makes a wonderful place to use for your reclusive gazillionaire’s private retreat, and you can write your much more prosaic character being completely awed by how wonderful it all is – until that oh so convenient to your plot storm causes Problems that the two of them have to resolve (it’s up to you to figure out a convenient reason why there’s no staff on-hand for a place this big).
Or your conspiracy theory thriller can have the secret society holed up in a privately-owned castle to do their plotting. I’ll admit the idea of owning an actual castle has its temptations (what can I say? I am Kate the Impaler and a nice avenue of stakes to greet my enemies as they try to besiege my castle does have a certain visceral appeal). For that matter, said castle’s hopefully more or less accurate period décor can help a lot when you’re trying to visual who is doing what where in that historical novel or epic fantasy.
If you’re of a more down-to-earth bent and interested in uber-secure hideaways for your supervillain there’s always the former missile base conversion. These have the added advantage of being able to host your very own home-made missiles – as long as you can manage to fire the things without drawing attention to yourself, which is its own issue. No, they don’t sell them with decommissioned missiles, and I’ve yet to find any for sale outside the USA, but it’s a lovely thought, isn’t it? Your supervillian, his hidden base, his stash of suspiciously phallic missiles… Oh, the possibilities are endless.
You could, of course, grow your own, as it were. Find a nice-looking patch of land, imagine a castle or mansion or underground lair or whatever there, and go for it. It might even work better for you, since it would be indisputably yours.
So dream away, and use what you came up with.