I'm super-accomodating and always say "yes", even to very early drop-offs like 8 a.m. (although it's rarely that early, more often around 11 a.m. ish). I have them put the suitcases in a corner in the living room. I don't let them enter or see their bedroom until it's ready (around 3 p.m.), but I do let them use the rest of the house if they want to (most leave right away and come back later, but some want to use the bathroom, and after a long flight I don't blame them and I let them). I also give them the keys to the front door and their bedroom and tell them they're free to come and go. That way there's no problem if they return when I'm not home. I realize that not all hosts have this kind of flexibility (I'm retired so I'm always available), but it sure goes a long way in making a good first impression and setting a positive tone.