Good question and a similar problem arises with schools. I don’t think there exists a best practice yet. My suggestion would be that conceptually “a hotel” is a building (or set of buildings), and that if someone were using OSM to search for the Hilton Hotel they would expect to be pointed towards the building, not the grounds or carpark.

This means that the hotel building would be tagged tourism=hotel. The grounds are a leisure=park or leisure=garden with name set to “Hilton Hotel gardens” or similar. Carpark would be amenity=parking and name=Hilton Hotel carpark etc. But that’s just my view and as I say, I don’t think there’s a consensus yet on this question.