My husband and I are driving from Chicago to DC, Baltimore, and Philadelphia in June to go to these 3 baseball stadiums. Besides the top attractions in those cities, are there any places along the route, just outside these cities, or even in the city itself that would be worth visiting? We aren't huge museum people, but even more nature type parks that are unique, or any sites that are worth taking in? We will be out there for about a week and trying to determine how many nights to stay in each city. Thanks!