Three Mile Island south of Harrisburg.
The Rockville Bridge, just north of Harrisburg, the longest stone arch bridge in the world.
GettysburgCity Island Harrisburg. You can also bicycle along the Susquehanna River at Harrisburg.
I know you will have the kids along but, if you can get away or come back to the area in the future go see the
Yuengling Brewery. Even if you don't care for beer, it's a very interesting tour of America's Oldest Brewery.
The Pennsylvania State Museum in Harrisburg
The Millersburg Ferry north of Harrisburg
Twin Grove Campground north of Harrisburg along I-81
LIckdale Campground north of Harrisburg along I-81
Hershey Park Camping Resort, formerly Hershey Highmeadow Campground. But, it's near Hershey Park.