Here are some hotels in Myrtle Beach for the 2021 Labor Day weekend. There are actually quite a few rooms still available at somewhat reasonable prices. My search was for a 3-night stay Saturday through Monday, (9/4-9/7).
You can view hotel rates all up and down The Grand Strand by moving the interactive map.
Also, to give you a better idea of where these properties are, the Myrtle Beach Boardwalk is located on Ocean Boulevard around 10th Avenue N.