As a teenager there is lots you can do in Rockland county area as it is rich in culture, history and lore. I will not suggest you to hangout in malls and restaurants, even though there are some really good ones. Not to forget the Nanuet Mall in Nanuet. Palisades Center is another 4 level shopping center at West Nyack.
Rockland County has many famous histories homes and sites from the time of American Revolution. You can spend a pleasant evening sitting along the banks of the majestic Hudson River. Rockland County also has a number of parks and gardens. You can catch a nice art show in one of the many art galleries including 21st Century Gallery on 88 Main Street in Nyack and Art Essentials of NY on 25 Church Street in Monsey.
There are all kind of recreational activities like swimming, hiking, boating and camping. You can even enjoy ice skating, sledding and cross country skiing in winter. Try Anthony Wayne Recreational Area or Bear Mountain State park both on Palisade Parkway in Bear Mountain. For more information visit www.rockland.org