I've read both Scarlett and Rhett Butler's People, and they're okay, but neither holds a candle to Gone With the Wind. It's hard to do a good sequel or prequel/sequel to a classic. The sequel portions of the stories are also very different from one another.
Scarlett really was a "mule in horse's harness" , and had a hard time fulfilling the expectations of her society. Almost all her female peers (except Melanie) loathe her and I wonder how much of that attitude was due to snobbishness about Scarlett being the daughter of an Irish Catholic immigrant, instead of from the old Southern aristocracy. It took both money and breeding to be completely accepted in that social circle and I got the impression that Tara in its heyday wasn't half as grand as Twelve Oaks.