Our timeshare is at Edisto and we vacation there often.
If you picture a continuum with Myrtle Beach on one end, Edisto would be on the opposite end of that comparison. Nothing wrong with either place, just sayin'. Myrtle beach is big and very developed and bustling. Edisto is small and quaint and laid back.
Edisto Beach is mostly individual houses and small vacation developments. Wyndham has several different locations on the island and has a cabana on the beach with a free shuttle from all the different Wyndham locations.
Baypoint is our favorite. It is on the south end of the island and is on the river and marsh. It is beautiful. we've been there many times and there have always been dolphins in the river.
Edisto is a great place for cycling. Bike paths at the beach and on the island itself in the state park.
The only grocery store is a small Piggly Wiggly but the folks there are friendly and helpful.
You would be about an hour or less out of Charleston, a couple of hours from Beaufort (Byoo-fort) and 2 1/2 to three from Savannah.
They do a Low Country Boil onsite (Tuesday I think) and it is good. Activities depend on the time of year. Several nice places to get seafood.
George and Pink's vegetable stand is a good place for fresh veggies in season. The Sea Cow is a nice small restaurant. Whaley's is a good local bar/restaurant. (small but with lots of character)
Enjoy Edisto.