My older is 8yo and I NEVER let her invite any friends come to stay for the night. Ever. Yea... I'm awful like that. I don't feel comfortable with 3 hours playdates in broad daylight!
Mostly because I think that when kids see themselves without her parents (most of them) goes all shades of CRAZY. I know exactly how to keep it together with my daughters. But with craziness from other children? Nope. I can't handle this. The truth is most of them have behavior issues. Period. I blame them.