We let them be during the summer months and they tend to wake up around 10. During the school year, their lives are so busy and stressful that I strongly feel it's important for them to get some R&R during the summer. Also, imo, part of the fun of being a kid is the ability to goof off during the summer and stay up and sleep in. Of course all this changes if they have activities in the morning, but barring that…
I just read some of the pps- my kids do fine with this.