New York state is big. Depends on where you go. If you are talking about NYC area, maybe Hudson Valley area is good for you. I think West point is that area. Very pretty area.
You can check http://www.iloveny.com. Sometimes they gave you updates on foliage. I could not get that now: http://www.iloveny.com/site-search.aspx?search=foliage
I heard the Adirondacks area is pretty too. Leave may turn red around late Sept, early Oct. Never been there around that time. But if you go there, try to go to saratoga springs(http://www.nysparks.com/parks/saratogaspa). I personally like that little town and the state park. Very good for summer time too.
Finger Lake area is good too. Connell university is around that area. A few state park(http://nysparks.com/parks/) there is nice to go too. Corning is also a tour place. Corning Glass museum maybe good for your daughter. Watkins Glen state park is close too. Stony Brook State park, Letchwoth State park is nice for 楓葉 too. remember Mid Oct is usually good for these area.
Niagara Fall is good too. But Oct is too late to play with the water.
