For Nano, things are much clearer now. I think my wife and I are going to tag team on this one. We have our daughter in mind and want to write something that she can read when she's 7-10 years old with a heroine that she can identify with.
50,000 words is about 160 pages, so if we do 16 chapters with 10 pages each, you can call me butter. Like Stu Scott says, "call me butter, cuz I'm on a roll."