My DS is almost 3, and he only had his first night away just after Christmas. It was with my parents who live 2 minutes up the road and who he has had heaps of contact with since birth. He is completely comfortable with them, and I trust them with him. At a younger age I wouldn't have been comfortable with it, but he seemed old enough and comfortable enough so we tried it out (with the promise of a phone call to come pick him up if he got upset). He was completely fine - had heaps of fun. I did miss him though.