This is one of the most beautiful hikes in the area. It's about a 3-mile out and back along the Appalachian Trail up and down Waywayanda Mountain. It's a bit of a challenging hike (lots of rocks, switchbacks, and stone steps), but worth it. It's extremely popular, so the best time to go is during the week and early in the morning. There are a lot of ways to make the hike longer by starting in different spots along the Appalachian Trail.
High Point State Park is about 30 minutes from Camp Sacajewea. The view from High Point Monument, at 1,803 feet above sea level, is an awesome panoramic view of farmland and forest, hills and valleys in three states. The blue line of the Delaware River divides the ridges of New Jersey from those of Pennsylvania. There are lot of hiking trails (the AT goes through as well) and a lakes and ponds you can fish in.
Warwick is just over the border between NJ and NY, and it's one of Margaret's favorite places to spend a morning or afternoon. They are lots of different shops (Newhard's Home Source is the best) along Main Street, and plenty of food options. It's about 40 minutes from Camp Sacajewea.