i had to arrange disney music for a prety big windband/ensemble ( about 50 players )
did beauty and the beast, trew century fox in and pinocchio.
what i found about disney music is that they almost imitate that the frame does :). for examble when belle is at the fountain singing. and opens her book and speaks of a prince charming . you see a big castle. you then hear horns. they make it romantic like. but prety minimalistic. they take a lot of same material and instrumentate everytime differently. they play with there material. prety french like. a lot of windinstrumentes, secondly a lot of strings, and thin or short lines for brass to accent a moment, but mostly they just play chords. and collour. same with the xhylophone. its collour more then a new role.
i think there formula is just simply playing with your material. make it exiting, dreamy and beautifful. like kids. they have these eyes filled with wonder. they want to know everything. they want to explore and such :). i think you should have fun like a child when writing for these movies. i sure had fun while arranging ^^ haha.