Honestly if you are meaning in settings I prefer modern day as well. Not that I don't like world building just gets tiresome at times. As for the creatures or people I'm good with doing either/or/both doesn't matter to much with me. I've never done a horror rp before actually though I've always kind of wanted to try one.

That being I really like your nightmare idea. Its really interesting and original. I'm not sure who we would play in it though? Some of the people who have the money to sleep in the chamber? Or the ones that don't?