I think if you really want a "down" night then BW is the way to go. We love it and have stayed at the BW and will be there this May. There is a ton of things to do. You can visit the resorts around the lake and see there X-mas decorations and shop at there stores. You can eat a nice dinner at any of the restaurants at the BW or other resorts. You can ride a surrey bike which is really fun. Also, your kids can get their faces painted, your DD can get a hair wrap. You all can spend some time in the ESPN zone, have iceream on the BW and visit the shops. Also there are games for the kids to play and strolling entertainment. You can see jugglers, sword swallowers, magicians and musicians. It is so nice and relaxing too! Also, at around 9pm you can see the higher fireworks from Illuminations!
We also love DtD, but it isn't too relaxing! There are alot of shops and places to eat and have snacks. It gets pretty busy at night. I would definately plan a trip to DtD but not to have a relaxing "down" night.