Stafford will make a suitable mid-way stopping point on your way down to Columbia, and it's always better to spend time with family and friends than in a sterile motel room. But, Stafford is just off I-95 south of Washington DC, so it makes the I-78/I-81/I-77 route less than ideal. Also, there are two "Chesapeake bridges", the Chesapeake Bay Bridge which crosses the mid Bay between the Eastern Shore and Annapolis, and the Chesapeake Bay Bridge-Tunnel which crosses the southern end of the Bay between the tip of the Delmarva Peninsula and the Norfolk area,
Working backwards, with Stafford as your starting point for Day 2 of your drive, I-95 to I-20 to Columbia makes by far the most sense. The real question is: What's the best way to get from NYC to Stafford? There are three options: The straightforward way is to just take I-95 (the New Jersey, Delaware, and Maryland Turnpikes) all the way down to Stafford. It's certainly doable in a day although it wouldn't be a particularly pleasant drive and doesn't lend itself to stops for the kids. The second option would be to set out on I-78/I-81 as previously suggested, thus bypassing Philadelphia, Baltimore and Washington to the west. You'd then hook around DC and into Stafford by leaving I-81 at Middleton VA and using I-66/US-17 to Stafford. That would add about an hour and a half to your drive time, but would still be a very easy day's drive from NYC and would be both cheaper (no tolls) and more relaxing than the I-95 route. Possible stops along that route include Hershey PA, Gettysburg, Catoctin Mountain National Park, Antietam National Battlefield, or Manassas National Battlefield Park. The third option is kind of a mixed bag. You'd take the Jersey Pike to Delaware and then head south on US-13/DE-1 to US-301 to the Chesapeake Bay Bridge, crossing to Annapolis, and then staying on US-301 as it goes around Washington to the east and south, then using VA-218 after you cross the Potomac to get to Stafford.Again, the Jersey Turnpike portion of that route wouldn't be 'fun' but the Eastern Shore of Maryland presents possibilities including the historic town of New Castle DE, Lums Pond State Park, Terrapin Nature Area on Kent Island, and historic Annapolis (and the Navel Academy),
Different computer based mapping routines offer different capabilities and tools, but nearly all allow some sort of route manipulation. Sometimes this is a simple drag-and-drop utility where you click on a route and drag it to another point to be included in your itinerary, and the program finds the best route to/from that additional waypoint. sometimes you have to explicitly specify the waypoint to be included. Google Maps has the first option. Once you have a map drawn. just point to the route it has drawn, press the left mouse button, and drag the route to where you want it to be.
AZBuck