Myrtle Beach is a great place. There is lot's to do with kids or without them. There is about 14 (I think) miles of sandy beach, many quality places to eat, many places to shop, many venues of entertainment. (I accidentally got to watch the South Carolina Shag Dance Championships at a night club.) There are high quality shows as well.
A car is a necessity though unless you plan on just going to a beach front hotel and vegging out. The strip is reminiscent of any beach front resort you have ever been to on the east coast. If you've seen one, you've seen them all, but it is usually clean and safe.
If golfing is a part of the plan, well over 100 golf courses within a 24 mile radius ought to get your attention, everything from par 3's to championship caliber courses.
With a car, day trips are possible as well. It's a 90 mile drive to Charleston, SC from Myrtle Beach. There you have, amongst other things, a aircraft carrier that can be explored or you can take a ferry ride out to Fort Sumter, if you are into history.
One thing...if you are in a club on Saturday night keep your eye on the clock because at midnight all drinks disappear from your table. Pre-purchase doesn't cut any ice. The Sunday blue laws prohibit drinking and it is, or at least was, strictly enforced. Now you see it...now it's gone.