My yorkie, Bella, stayed for a sleepover from Sunday through Thursday. Most of the dogs were bigger, but she fit right in. There are at least 3 humans watching, playing and loving on these animals at all times that I checked in. They clean up pretty fast after the dogs.
The only complaint I had was that she smelled pretty bad when I got her home. However, she played for 5 days with all the dogs, so if that is my only complaint, just have them bathe the dog the day you pick your pet up.
I'm sure I will be taking Bella back for play days and sleepovers.