I've not stayed in any themed or unusual places but my favourite place was Ruthin Castle in North Wales. They have peacocks roaming the grounds. When we stayed it was mating season and in our room were some ears plugs and a postcard from the peacocks apologising for the noise. The grounds are also meant to be haunted by the grey lady and while we were looking for the grave one of the ground keepers asked if we wanted to go in to the dungeons and look at the bats. I adore bats and it was the only time I had seen them roosting besides on the telly.
http://everydaybitsandbobs.blogspot.co.uk/2014/03/ruthin-castle.html