What kind of room or setting does a residential, indoor spa or hot tub belong?

I’ve seen the glitzy pictures from luxurious homes in typical advertisements. But I am not ritzy in the glamour sense. I just like a few nice things. They really make a house or home special.

A few unusual or very nice touches can really emphasize a lot. I am in the process of designing a house—a relatively small but lofty space. I really like the idea of having a 7×7 or 8×8 foot spa—the kind that can be used by 1–4 persons (though usually just one or two people). The traditional bathroom just doesn’t seem the spot for these.

I am assuming these are more “soaker” in function than for actual baths / cleansing. Its the therapeutic nature or the water itself and you don’t use soap or shampoo in them.

But what setting is best, functional for this, without being TOO ostentatious or glamorous?

What kind of room or area do you put one in?