I've gone to the Stowe Balloon Festival for the past two years. I imagine that it'd be a wonderful thing for a 9 year old girl to see. It's fun. They blow up the balloons right there on the back lawn of the Stowflake and launch them. They are so massive and so beautiful.
The event is sometimes canceled if it's too windy or rainy.
I always feel like the cost of it is a bit steep for what it is. I had fun when I went but I doubt that I'll go again. Bring some lawn chairs.
The Stoweflake is a fine place to stay. It isn't the Four Seasons ... but it's clean and nice.
If you can, bring some bikes. You can take advantage of the Stowe Rec path, which goes right past the Stoweflake. Also, the Stowe Farmer's Market is on Sunday ... it's a really nice event.