Just outside of the entrance to Marriott's OceanWatch, you have "Hook & Barrel". Right next to "Hook & Barrel" is "Croissants Bistro & Bakery" which we like for breakfast.
https://hookandbarrelrestaurant.com/
"Sea Captain's House" is on the beach and has been around for at least 50 years. It's one of the more upscale seafood restaurants in the area.
https://www.seacaptains.com/
There's "Crab Catchers" in Little River on the Intercoastal.
http://crabcatchers.com/
We usually drive down to Murrels Inlet one day and go to one of those restaurants off the Murrels Inlet Marsh Walk (Dead Dog, Drunken Jack's, etc...)
https://marshwalk.com/
We usually drive to North Myrtle Beach to go to "OD Arcade & Lounge" for one of their reasonably priced daily specials. They list their daily specials on their website:
https://odarcade.com/north-myrtle-beach-ocean-drive-od-arcade-and-lounge-happy-hours-specials In addition, they are one of the few places that have deep fried banana peppers which go quite well with cold beer.
We also usually go to "Rip Tydz" to eat when their calendar indicates that they will have live music. It's a very large bar/restaurant with ocean views. They are located on the beach boardwalk.
https://riptydz.com/
There is also "Mr. Fish Seafood Market & Grill"
https://www.mrfish.com/market-menu/
We prefer the breakfast restaurant "Eggs Up Grill" over "Johnny D's". We go to "Eggs Up Grill" a few times during our stay at Myrtle Beach. They have 2 or 3 locations in the area.
https://eggsupgrill.com/
Enjoy your stay at Marriott's OceanWatch!