Community theatres look for shows that will bring in money. Often, what they look for are shows that are well known and will be popular with the town/neighborhood. Another factor is cast size. While a show with only a few actors is great for scheduling and staging (and budget if they’re paid) a larger cast will bring in more friends and family to come and watch them (read: $$$) But a large cast means a bigger budget for costumes, etc. So when do you use a small cast show and when do you use a larger cast?
What you will often find is that a company will do a few small-cast straight (non-musical) shows and at least one very popular large-cast musical. This is where the bulk of the profit is often made. Popular and profitable musicals will often get repeated every few seasons, and not just at one theatre but usually throughout the area.
Other factors in choosing a show include:
Cast composition: mostly female cast, mostly male cast; specific ethnicity requirements; children; animals etc.
Technical elements: skills, time and budget
Appropriateness for the space: doing the musical The Lion King in a tiny basement black box might not work well.
As a stage manager, you should be aware of how shows get picked. And you should also be reading plays. Once you have some experience, you can read plays and make suggestions or recommendations on what shows might work for the space.
Take a look at the list of shows the theatre has done recently. Most likely people will be talking about them while working on the current show. Read the plays and ask questions.
The Awesome Stage Manager