We have been twice first week in December, and once first week in October. DH and I both think
MNSSHP party is much nicer than MVMCP, especially for kids. They give you a Halloween bag as you enter and there are "candy stations" all over, where adults and children alike get candy. It's fun. I also like the Halloween parade better than the Christmas parade, fireworks are neat for both. The Food and Wine Festival is fun also, but I'm sure the kids won't find it the greatest, but I don't think they would think the CP awfully great either.
Even though the weather in December has been nice for us, it is "iffy" as far as pool weather and in October we were in the pool everyday. It was actually very hot last year when we went. With the little ones that you have, I would opt for October and save December for when the kids are older. I know it sounds beautiful, and it is, it's REALLY nice as a couple too, very romantic with the Christmas decorations and music, but it IS a toss up for us as we really think the Halloween party much more fun (even the special activities and shows at the christmas party are not "geared" as much to kids, especially little ones.)
We also really like the Food and Wine Festival. October would be my advice, at least for you right now.
I'm REALLY excited, as we are going in a couple weeks and are "hitting" the last week-end of the Food and Wine Festival and Festival of the Masters Art Show (we've never seen this before). (Also Soap week-end, but I'm not a soap opera fan, so I"m stearing clear of that crowd). Only thing that would make it better is to have the Halloween party, but you can't have everything. I'm am hoping that by the end of the time we're there, there might be some Christmas decorations up, that would be cool.