As a former resident of the East Coast (DE, MD, NH, ME) I wouldn't call any of your targets so far a "National Park of the East". I'd also have to ask if you're interested in other parts of the (small letters) national parks system other than the designated (capitals) National Parks. If so, there are some great examples of such in the
Midwest.
My parents grew up in Wisconsin. We'd visit every other year and most of my cousins are still there. So locations such as
Apostle Islands,
Picture Rocks and
Sleeping Bear Dunes National Lakeshores, and the
Saint Croix National Scenic Riverway are well within striking distance of places already on your itinerary, but well worth any slight detour to get to them.
I often recommend slightly off-the-beaten-path or lesser-known attractions over the ones that are on every other tourist's 'must see' list. The Great Lakes region is no exception. When you start with the advantage of all those woods and all that water frontage, it's hard to go wrong.
AZBuck