Open Forum

The collaborative Arts Dept event worked well for me in my first school.  The visual arts teacher and his students did the scene painting, and the band/choral director put together a pit band for Brigadoon the first year I was there, and My Fair Lady the second.  It was a fairly rural school without a lot of resources devoted to the arts.

At my next school, also rural and low wealth, no one wanted to collaborate, but there happened to be a lovely woman in the community who could play the score of a musical very well.  She volunteered to come a couple of days a week to work with us, and she was the only musical accompaniment.  In the eight years I was there, we only did two musicals, and only when we happened to have a lot of singers.

The shows in both of those schools were extracurricular. 
At my current school, we do a musical every other spring in a cluster of theatre and vocal music classes that meet together.  Our choral director directs the music and plays piano for the shows.  I direct and serve as technical director.  We commit to casting every student, excepting a stage manager and asst. stage manager, so we have to choose shows with a large, flexible company.  We do use paid choreographers some years, but we often have a student who is up to the challenge.

I think it is probably wise to take stock of the resources available to you before choosing a show.  Ask the students if there is a local person with experience playing from a conductor's score who might be willing to work with you.  Ask your faculty members.  Find out if any of your students have had multiple years of dance and might be interested in choreographing the show.  If those other arts teachers are really on board, it could be a great experience, provided you divide up responsibilities very carefully before you start rehearsal.

I like large cast shows because I can assign understudies, and the less experienced actors improve their skills while being part of something big.  Some large cast shows that we have had great fun with include Once Upon a Mattress, Back to the 80s, and Changing Minds.

Good luck.