There's a lot more to do in Toronto, for sure, but Georgian Bay is a nice place to just go and relax and enjoy!
But if you're planning a few days in Toronto, there's more than your fair share of fun things to do! The CN tower is quite fun and a must-do, even though there isn't much to do, it's a really fun experience. There was a mini-putt course at the bottom, think it's still there.
The Toronto zoo is a lot of fun! A definite must do for me every time I go to Toronto. There's a lot of walking, and it's very open, so maybe do it on a day where the heat/humidity isn't super hot.
If you want to do amusement parks, Wonderland is really fun. It's more thrill rides and such, but there's a waterpark too in the park. Ontario Place is a smaller park, not really many thrill rides because it's much more of a family themed park. There's a water park too!
Casa Loma is fun too. Since your daughter is older she might enjoy it, but it is more adult oriented. It's basically an old castle that you walk through, it's very historical and the archicheture is gorgeous. You can climb a few of the turrets and look out over the city.
We always go to the Hocekey Hall of Fame, LOL, but unless you are a huge hockey fan, it's not a huge must.
Oh, I almost forgot about the Ontario Science Centre! Again, lots of fun and there's a lot of hands-on-displays that appeal to both kids/preteens as well as adults!