Heres the places ive stayed and they are all great locations for mustang week.
LandMark ( 2 years here)
SeaGlass Tower
SeaDip
I am staying at the Boardwalk this year. Keep in mind im on a 23 year old budget with my girlfriend but all of these places are very nice places and only cost around 1k for the week depending on the place.
I stayed at a condo one year in north myrtle but i cant remember the name and i wouldnt recommend it anyways.