It is 381 miles according to Google Maps for that drive and both Baltimore Maryland and Washington DC are worthwhile Halfway Points.
One halfway point between Milford, PA and Virginia Beach, VA is Kitts Hummock, Delaware. You could also consider Baltimore, MD a halfway point.
The halfway point between Buckhannon, WV and Virginia Beach, VA is Troy, VA 22974, USA.
Hardee Cross Roads, North Carolina is halfway between Columbia & Virginia Beach
Milford, DE
Vance, SC
Lexington, VA
Meadow Bridge, West Virginia
Chesterfield VA is about halfway from Allentown to Myrtle Beach.
Grantsville, Mississippi is halfway between Slidell & Nashville
If you take I-95 all the way to Richmond before cutting east to Virginia Beach, your halfway point is Baltimore. If you cut down through Delaware and take the Chesapeake Bay Bridge & Tunnel (toll), your halfway point is Smyrna, DE.
Interstate 20, Eastaboga, AL 36260
The halfway point from Fredericksburg, VA, and Charleston, SC, is Dunn, NC. This is the route halfway point. The midpoint (if a straight line was drawn between the two places) would be in Angier, NC.