"At the Zoo", "Down on the Farm" "Wild Things" - can feature animal-related songs (zoo animals, farm animals, jungle/wild animals) and could mean some cute costumes.
"Candyland" with music related to candy and other sweets
"Around the World" with songs from different countries
"Across the USA" with songs about different states or America as a whole
"Once Upon A Time" with songs based on storybook characters like Peter Pan, Aladdin, Cinderella, or Beauty & The Beast.
"Kaleidoscope" - songs about different colors
"Sea Cruise" - songs about water, oceans, beaches
"Our Favorite Things" – have your students list their favourite things and choose songs based on them.
"Wither the Weather" - songs about the weather
"All the Jazz" - jazz songs and dances and improv
"Rising Stars" - sings about stars, planets, the cosmos.