C.C.
We absolutely loved Mansio Mens Montessori in Geneva. It's very small and private and personal and my son did great there! The director Janet is no-nonsense but very passionate and effective!
My boss sends his kids to Bridges Montessori in St. Charles and he likes it for his son who is very detailed but his free spirited & very social daughter switched to public school as it seemed like a better fit for her.
I also have 2 friends with kids at Prairie View Montessori in North Aurora and they seem very happy there.
Good Luck!