I’ve been looking for nodes or code progressed enough I can manipulate to use the method your talking about with my skill level. I’m using rhythms object host top face for a script placing trees on floors, if that’s the same method. However it started failing with more complex geometry. Having a stable method to get top faces of floors to intersect with for points or other things like planes would be amazing!
There’s a Revit file here with a curious shape if you wanted to look.