How tall are your kids. Most of their rides have a 48" height requirement or are for little kids. If you have kids less than 48", I would suggest driving the extra hour and going to Busch gardens. We just went this weekend and had a blast. They have a neat little bird area where you can feed the birds this liquid stuff and the birds will sit on your shoulder (or your head) and drink out of the cup. If you have little kids, they added a new Sesame street area that has a few little rides and a really nice water play area. I would also recommend the Sesame street character breakfast. We went on Sunday and there were only about 10 families. We got to spend an hour with the characters (Elmo, Big Bird, Bert, Ernie, and Cookie Monster). Each character did some songs on stage. Between songs, the characters would go out and dance and play with the kids.
We did do Kings Dominion early last year, and there were only 3 or 4 rides we could go on with DS. We spent most of the day watching him ride the kiddie rides that he really didn't enjoy very much. We decided that we would wait until he hit 48" to try again. If everyone in your party is 48" and you are looking for roller coasters, then I think Kings Dominion would be the better park.