The Carolinas do not have any large coastal cities.
Charlotte is 3+ hours inland and
Raleigh is 2+. The largest coatal city in NC is
Wilmington, which is a great city, just not large (in comparison to SD) and in SC you have
Charleston.
If living in a large city outweighs the ocean, I'd suggest Charlotte. If the opposite is true, take a closer look at
Wilmington.
Another thing to consider, if easy access to the mountains also seems nice, Raleigh and Charlotte, NC or
Greenville, SC would be your best bet.
The Carolinas are a great place to raise a family. I personally know many native Californians that needed to get away (mostly financial) and have found this to be a great home.