Orange County offers so many great things for children of all ages to get involved in such as sports, boy scouts, 4-H, etc. My children have made some great friends by being involved in some of these groups.
Yes there are many places to meet other kids. Castle Fun Center in Chester is a great place. You have roller skating, gokart, video games and then down the street is a tennis center you can sign up for tennis lessons. Mount Vernon NJ is not far there is a water park in the summer and skiing in the winter. A lot of camps that are not too expensive in the area. Schools offer many summer activities and school time activities.