Seems to me what would fit the bill best is a ball. A real period ball; with waltzes, and dance cards, and flowers. There are lots of venues at the resorts where such a thing could be done, and they could do them seasonally.
One wouldn't even have to wear a true princess costume; a floorlength ballgown and gloves are sufficient.
Personally I think grown women need more occasions to get really dressed up in formal gowns. I think that the dearth of real-life formal-dress occasions for grownups contributes hugely to wanting to dress up like a Disney princess -- it seems like the only chance one gets to wear a ballgown now happens before one is 17 years old.