Sixth Street Playhouse presents a family musical that explores the meaning of friendship in a vaudevillian adventure adapted from Mo Willem’s children’s books. $34. Sept. 16–17 & 23–24. 10 a.m. & 1 p.m. Charles M. Schulz Museum. 2301 Hardies Ln., Santa Rosa. tinyurl.com/j5nn3y7v.