My dd is only 3... If she is willing to stay asleep, I let her sleep! She usually wakes up around 9, unless she is in a growth spurt or sick.
In my family, we were able to sleep in during break as much as we wanted, unless we had something going on that we needed to get ready for. We were pretty much responsible for feeding ourselves breakfast and lunch, so it wasn't a hassle at all for my dad. We knew that dinner was at 6:30, and we would be expected to eat what we were served. We also knew that bedtime was at 9, with lights out by 10 even if we weren't tired. It was a pretty good system, IMO. We learned firsthand that it really sucked sleeping in until noon, only to have to lay in the dark for hours trying to sleep. Lol.
When I lived with my grandma for a while, she would wake us up by 8 every morning and put breakfast on the table. She prepared and served lunch at noon, and dinner at 6, with the same bedtime rules as my dad. It was also a good system.
I think the best way is whatever works for your family. I know I LOVE getting chances to sleep in, so when my DD is older she will most likely be allowed to sleep in as late as she wants.