I've got experience with a couple gyms in the area:
(Used to be FLIPS but is now) Lake Forest Gymnastics Academy:
Owned by the same people as Libertyville Gymnastics Academy. I had a really abusive coach that I didn't realize was abusive until after I had transferred gyms - this was my first gym. All the other coaches were great. They have a pretty good Xcel Program.
*EDIT: Upon pulling up the website this coach is no longer there. Her name was Tabby if you do choose this gym and come across her.
Cary Gymnastics:
I was there for a year. They have a very over-crowded Xcel program that tends to skew very young, think mostly elementary school age. The coaching was good. The only thing was that they wouldn't really work with you on mental blocks or injuries; everything was a very one-size-fits-all approach. Which didn't work great for me, but would probably work well for your average gymnast.
Crystal Lake Gymnastics Training Center:
I did a tryout at the gym and decided it wasn't for me. They wanted 4hrs 3x a week for Xcel Gold. I wasn't willing to give up that much time. This is where the D155 HS team trains, so if you're in that school district, that could be good, because you would already know the environment if she intends on doing HS gymnastics. During the tryout they did for me, they moved the springboard on me, refused to move the height of the vault table, and screamed at me when I missed the vault table because things weren't set up right. I also heard some scary stories about the Xcel coach. They had one coach for about 6 girls, though apparently there were like 10 on the team, and they had no expectation that you consistently show up for practice on time, or at all. Their team tends to be mostly older middle and high schoolers.
Huntley Unlimited Gymnastics:
Did a tryout here too. They never got back to us after the tryout despite calling and emailing. They have a beautiful and large facility. Not sure about team size or coaching as the tryout they had me do was one on one during an open gym.