Maybe first you should decide if you want to make only one animation theme (ie: Mulan, Frozen) or if you are going for a little bit of everything. You can mix up some of the 'medieval' looking princesses (Snow White, Tangled, Sleeping Beauty) or use the theme parks as inspiration.
Some suggestions:
Lilo & Stitch : Cabana and Cabin series ;
Cinderella : Classic series , Blue series , Regal, Pav? and Princess series;
Sleeping Beauty: Gorgeous series, Mixed Wood, Rococo series; patchwork series, spinning wheel
Mulan : Exotic series; bonsai set, some of the Japanese-style set (I know she is Chinese); baby panda, mama panda
Frozen: Ice , Rococo, Snowman, Scandinavia series
Little Mermaid: Mermaid series; Fish Set
Tangled, Ranch , Rococo series, Antique set; loom (sold by Savannah), sun, sunflower, sunflower stereo
Beauty and the Beast: stack of books, big bookshelf
Snow White: Mixed Wood, Forest Floor and Wall, Mush Closet and Dresser, Ranch, Rococo series; apple set, pine set
Tinkerbell: Mushroom series, flower chair, flower table, flower wreath, flower display case; lily lamp, lily record player, lily-pad table
Nightmare Before Christmas: spooky set
Wreck It Ralph: Pipe , Sloopy (for Ralph), Sweets (for Vanellope) series, Nintendo set; arcade machine
Princess and the Frog: Cafe set, Frog Set; lily lamp, lily record player, lily-pad table
Alice in Wonderland: Chess set, cup of tea, birthday set
Hercules: corinthian post, cornucopia, pantheon post
Toy Story: Ranch series and Western theme(for Woody), Near Future series, Space and SF theme for Buzz
Aladdin: Magic Lamp, objects sold by Savannah
I'm sure there's much more, I'm just starting the series and I found a good site to look.
As for NPCs, Prince the frog would go good with Princess and the Frog and Colton the horse would be a good 'prince'
