I have only been to North Myrtle - which isn't quite as developed as you picture there - but after hearing lots of slams on the place by Washingtonians my whole life there, I was really surprised how nice it was. Funny that you compare it to Panama beach - aka the "Redneck Riviera" - because that's what most people in DC do too. I say Myrtle gets a bad rap. Your pics look totally great and fun.
It wasn't as J-Crew as the Outer Banks, but the beaches were solid and fun and I liked it there! It was a little far from DC, so I always went to the OBX (because Virginia beach has pretty much the same rep as Myrtle).
In retrospect I wish I'd explored the entire coast better from Cape May to Jacksonville while living in that part of the world.