Antidotally, Glencoe's taxes trend higher. But that shouldn't be your only criteria in differentiating between the two suburbs. They both are in the New Trier district, both on the train line with an easy commute to the city, both have excellent schools.
In Glencoe, there are three schools: South (elementary) West (middle) and Central (junior high). Cleverly named! The great thing about Glencoe is that every child in Glencoe goes to these schools, making it a close community where everyone knows each other.
Winnetka has a unique school system. It has a Progressive Education system, which is really unlike anything you can find in a public school system. It focuses on indiviualized instruction, hands-on learning and attention to the development of the whole child. Students in the Winnetka system don't recieve letter grades until 7th grade, although there is extensive conferencing and a unique portfolio review by the students. For more information on the Winnetka schools, visit http://www.winnetka36.org