I think it sort of depends on who you are taking and how well everyone gets along.
We just did a Grand Villa with some friends of ours. There were a total of six people - so we had plenty of room. The two adult couples (hubby and I, friends of ours) got bedrooms, and then my daughter and her friend got the third bedroom. There was lots of room and we spent lots of time together without tripping over each other.
When I took my family, we did two two bedrooms. It was my parents, my sister, her husband and her two kids, and my husband and I and our two kids. My sister, parents and nephews got one two bedroom. My family got the second (had my other sister been able to make it she would have taken our second bedroom and my kids would have ended up on the pullout in the living room.) Since my brother in law and nephews can rub my husband and I the wrong way (as family that you love sometimes can, especially when their habits conflict with yours), this made for a much more pleasant trip for us. That would have been ten in a Grand Villa - but sharing mornings with three of those people would have driven my family nuts - and Disney trips can be stressful enough without the family drama of people who are still awake at midnight, and then complain when you are running the coffee maker and getting everyone moving at 7.