Beach road trip ideas in the Carolin as or the Virginias?

so me and some friends want to take a road trip. we are from michigan and were thinking of the virginias or the carolinas because we want to goto the beach but not go too far! so if you have any ideas or recommendations on where to go and where to stay that wouldnt be too expensive that would be awesome! also we are all 18 so if you know hotels that allow 18 year olds to check in it would be greatly appreciated!