So if you have never done OBX of Myrtle you really should be both at sometime. They are vastly different. OBX is all about the beach, fishing, relaxing. There is plenty though for a week such as Wright Brothers, Jockey Ridge, 3 of 4 light houses, day trip to Ocracoke. Myrtle beach can be all about the beach or it can be as busy as you want to make it with all there is to do. Both locations have great campgrounds for direct beach access. At OBX I would suggest KOA or Camp Hatteras and if you go once NC schools are back in session you will have plenty of space in the campground to spread out. Same for Myrtle if you go back once schools start. In Myrtle we like Lakewood, Pirateland, and Ocean Lakes.