Never been to Waverly Hills myself - it's a bit far from Rendlesham for a casual trip - but I've read a fair amount about it and the 4th floor stuff keeps coming up in accounts. The "body chute" gets all the attention but it does seem like witnesses consistently report that upper floor feeling more than anywhere else in the building.
What I'm curious about is whether people who felt followed actually saw or heard anything specific, or is it more of a pressure/presence type sensation? Because those two things are pretty different in terms of what might explain them. Old buildings creak and the mind fills in gaps, but consistent reports from unconnected visitors in the same area is harder to dismiss.
Anyone done a proper overnight there rather than just the public tours? I'd imagine the controlled tour environment changes things quite a bit.