Jensenman/Curmudgeon is dead on.
Folly beach is the best beach. The Isle of Palms and Sullivan's Island have been bulldozed by developers long ago and the place has lost all of its old beachy charm. Also, alcohol is illeagal on Isle of Palms and Sullivans beach, It's not that way at Folly(just no glass containers or cans, pour it in a cup). Folly has tons of old beach cottages left on it from the 1950's and 1960's. Plenty of interesting folks. IOP and Sullivan's are just so plastic, It made my face hurt... Almost like Daniels Island, Manufactured happiness for the transplants with money.
Go for a Drive up Ashley River Road in West Ashley. It's a great drive with tons of nice Live Oaks arching over the roadway. I've been told before Hugo it was even better. Too bad. Go to a plantation.. All are different, none are bad.
Go to http://www.thefathen.com/ On Johns island. It's freaking amazing.
Hymans is for Chumps. Totally touristy crap. Go one block over and get a table at Hanks.
Go to the Wreck of the Richard and Christine, Jensenman is right.. It's Awesome. I loved the restaurants there when I lived there...
It's closed for the season now, but http://www.bowensislandrestaurant.com/ Is a famous dirty crappy oyster shack that serves amazing seafood.
http://www.jackscosmicdogs.com/ <--- awesome
http://www.sesameburgersandbeer.com/ <-- SUPER AWESOME
http://evopizza.com/ <-- awesome.
http://www.hometeambbq.com/ <-- Firey Ron is my homeboy
http://www.ilovetheglassonion.com/ <-- Heard it's good, but never went.
For Breakfast:
http://threelittlebirdscafe.com <-- Good but not too scenic
http://www.lostdogfollybeach.com/<-- Go there for breakfast. Go early the lines can get long and then go for a nice walk on Folly in the morning.
South End Brewery in Charleston is OK, not great. Try to find something from Coast Brewing on tap.
You won't go hungry in Chucktown.
The best kept secret in Charleston is http://www.dinewithsal.com/ . That restaurant group has some of the best and cheapest restaurants in the city. The quality is top notch, and the prices are rock bottom. Amazing specials every night and before 7pm mon-thursday it's half price bottles of wine. The Mustard Seed and Boulevard diner are my favorites.
The Angel Oak is awesome.