this would be usefull, when a hotel closes during winter or for maintenance reasons.
If you could click on the "day" in the dashboard to skip all reservations without having to enter for every room a reservation, it would be very nice.
I would create a seperate tabel for that and query it as a "right outer join" before showing the calendar.
The moment you have 1 reservation, you should no longer be able to set the hotel as "full", to keep it simple
In my case, I have a hostel that is rented during the weekend for 1 full group, during the week I rent room by room.