Help With Planning 5 Year Old Girl's Birthday Party?

My niece is turning 5 in early April and I am helping my sister plan her birthday party (co-ed with a few more girls than boys). It is being held in a picnic pavilion at a local park, and my niece wants a Rapunzel party (from the Disney movie Tangled). So far, we are only set on the invitations (little golden suns with 'Wanted: You! At My Birthday Party!' on the inside resembling the Flynn poster, then the party info), and little lanterns made of paper hanging from the streamers) but maybe there are better options too? Any ideas for more decorations/activities/food(including the cake)/party favors? Should we hire a Rapunzel? Any specific answers will be greatly appreciated!