Summer Myrtle is nearly impossible, this late into the year. You can rent, though. Myresortnetwork and redweek are probably best options. The Wyndham resorts can be reasonable to rent.
I see the original poster mentioned the Marriott resort. I own at the Marriott in Myrtle Beach. I also stayed at the Wyndham Ocean Boulevard last summer. The Wyndham was nice, but the rooms are SMALL and there is no resort feel at all. The Marriott is in a class all by itself. Beautiful pools, walking paths, kid play areas, wide open spaces, etc... They Wyndham has none of this, but it is still very nice, just very different than the Marriott.
Wyndham SeaWatch seems much nicer and bigger than Ocean Boulevard, so if I were buying a Wyndham, that is where I would want to stay. I almost bought Wyndham points for their Myrtle Beach properties but in the end I went with Marriott. Cost me A LOT more in buy in costs but the dues are actually cheaper and having been to both properties, all I can say is once you buy Wyndham, forget all about the Marriott and don't even drive by it or you will have regrets.
The cottages look fantastic, but they are some distance from the beach. Still, the cottages are real houses and are no more than half a mile from the beach.
Ocean Boulevard has a fantastic location. Loved being able to walk to downtown North Myrtle Beach, but the pools are so ordinary and covered in almost complete shade all day long. There are no open spaces and the place is just so closed in. With that said, the views are great, even from the tower across the street, which is where I stayed.
...and ask a Wyndham owner to explain the ARP. There is some restriction where you only get the 13 month advanced reservation period on your current year points. If you buy a smaller contract, that is great, but you cannot bank your points from one year and then try to book next year at 13 months out with any banked or borrowed points? I came from the world of Disney and most owner bank and borrow and book within thier advanced reservation period for their home resorts. Same is not true with Wyndham. If you want a week in Myrtle that costs 300k points but you only have a contract that gives you 275k points, you cannot book 13 months ahead of time because you would need to bank or borrow points to get your week. You can still book a week with banked/borrowed points (and borrowing might not even be allowed) but you have to book within the normal reservation period, in other words you can't book until all the other non-myrtle beach owners can book.