If you are coming across I-10 to I-95, I'd first head south and hit St. Augustine, FL if you've never been. Spend a few days there. We like
North Beach Campground. It is on A1A, just across from the beach.
Heading north on I-95, check out Jekyll Island, GA. There's a campground on Jekyll Island and several at the exit (exit 29). We like
Blythe Island Regional Park and Campground and
Coastal GA RV Resort. Savannah, GA is good for a day or two, we like
Skidaway Island State Park.
We really like Hilton Head, SC and Charleston, SC and could spend a few days at each location. Both are a little ways off I-95. We've never camped on Hilton Head. We really like
Oak Plantation Campground. It's the closet campground to downtown Charleston. James Island County Park is very popular, but might be tough to get a reservation on short notice.
Not much of interest to us in NC along I-95. We've only done quick overnight stops in NC. VA is a beautiful state, although northern VA's brutal traffic sorta ruins the rest of the state for me. We've stayed at the KOA in Fredericksburg. We got stranded there when our tow vehicle broke down in late November. It seemed like a nice campground with lots of Civil War history close by (if you are in to that).
Western MD is beautiful, but might be too far off your route. We like Rocky Gap State Park (about 2 hours west of I-95 without traffic) and there are some okay state parks south of Baltimore. We stayed at Patapsco Valley State Park in a pop-up back in 2005. We had electric and water, don't know if they've upgraded sites since then. The eastern shore of MD is nice as well, but never camped there.
Nothing nice in DE along I-95 as far as I know. There are a few decent campgrounds in NJ. Most of the campgrounds in the southern half of NJ are at the Jersey Shore, about an hour from the NJ turnpike. There are a handful of campgrounds in NJ within a 30 minute drive to Philadelphia. Or you can stay in PA. Perhaps stay in Lancaster, Amish Country, and take the hour or so drive to Philadelphia. There are closer campgrounds in PA to Philly like the West Chester KOA.
Can't help with NY.
-Michael