One of my favorite places to visit in Maine is Wolf Neck State Park. It is on the ocean and has a great many trails which are wide and well maintained. Trail maps are available at the gate and it has many picnic tables with grills in the woods or on large green spaces. It is very family friendly. It is not crowed so thee are secluded areas if you prefer to be alone.
On the way up I stopped by the Royal River for a shot of the lower falls. The lack of rain has left it not as dramatic as it can be during spring run off. I the fall it takes on very dramatic fall colors.