I am surprised how friendly the locals are! I have lived in a tourist trap (DE beach resorts) for almost 20 years, and we have the most ignorant tourists at times. Locals are NOT that welcoming towards out-of-staters. But in South Carolina....locals are SO FRIENDLY!! As a born Yankee, all that friendliness surprises me. Pleasantly surprised!
This isn't necessarily particular to Myrtle Beach, but, to me, the best lodging option when vacationing on the beach is to rent a condo or house, depending on the size of your group. This is especially applicable if you are traveling with a large number of people, because it allows all of you to stay in the same place. As opposed to a hotel room, you get your own kitchen, laundry machines, etc. It's more like a home away from home. Several Myrtle Beach rental agencies can be found on the web.
Especially on the 4th of July, if you go to the beach at night, the place is covered with fireworks people put off on their own. There are fireworks sold everywhere, and even on regular nights, you'll catch people putting them off on the beach. shared with friendly locals and a few beers, its definately something you must do at night.