With reception it depends on how you play it. If you have full rooms, there is no need to have someone at the desk, why try to check in more people when you are full? With events to unlock I might not have a full hotel, but need to move staff about so may leave the front desk empty so I can get the events I want.
I used to leave the front desk staffed all the time, until I realized it was sometimes detrimental to have people waiting overnight before I would have a room available. I mean really, in a VIP hotel who is going to do that?
Only time I could see it useful is if you are trying to get a specific guest, but if you are full up why would you attempt to check more people in when you don't have empty rooms? Again, its all your strategy and how you want to play it.