This sounds like a dream come true. There is porn yes, but it's all fake even when done by true couples...the moment you know a camera (or someone) is watching you it becomes acting and not doing the deed itself.
So, I really wish to be able to see couples unaware of my presence, without breaking their intimacy or forcing anything...the perfect way is the way you do it.
I really wish you'd leave us the hotel name or other suggestions really lkne...because as said before, I have been in hotels facing each other, but the curtains are almost always closed.
So, it has to be a visible hotel yes but also you need people willing to let the sight open.
It doesn't have to be high, if it faces a lake for instance then people usually let the curtain open.
Maybe you'd be able to leave me the name of the hotel if there is a way to do it privately ?