J.O.
Castle Hills is technically in Lewisville (long story but basically Carrollton didn't want it, Lewisville did). It is upper end, houses range from the 300's to the multi-millions. It's very much a family-oriented community -- parks everywhere, pools, tennis, basketball, golf. This is their website: www.castlehills.com
Here is some information on the elementary school:
http://www.lisd.net/main/schools/castlehills.html
Right now the middle school is Creek Valley: http://www.lisd.net/main/schools/creekvalley.html
and the high school is Hebron High: http://www.lisd.net/main/schools/hebron.html
But another middle school is in the process of being built (across Parker from Castle Hills) and the high school is in the planning stages.
Hope that helps.