Lisa,
Bringing your girls down for their (and your) first princess experience is a memorable event!
There are a few options to go with. Let's start with your resort. Here are my recommendations, by resort class, and why;
Deluxe: Grand Floridian
Of all the deluxe resorts, this has the most princess-friendly theming. Character meals with Cinderella and Mary Poppins are here, as well as a princess tea party event.
Moderate: Port Orleans - Riverside
The new Princess themed Royal Guest Rooms provide an over-the-top atmosphere in a still-budget friendly setting.
Value: Art of Animation
While Ariel has a section here, you may still prefer to lose a bit of the princess theme for one of the Family Suites.
As for must do events, a princess character meal is a nice treat.
Cinderella's Royal Table is the long time favorite. But if they have a particular favorite, there might be other options. For instance the Cinderella Happily Ever After Dinner at
1900 Park Fare has more characters from that movie.
Make sure you are ready for character meet-and-greets throughout the parks. Check your
My Disney Experience app for times and locations.
A final suggestion that is very popular is
Bibbidi Bobbidi Boutique. It is not for my girls, but it might be a great final twist to the trip for yours?
Write me back if you want to ask any further questions to a dad in the same boat as you!
Have a magical vacation!