Having just opened PETER AND THE STARCATCHER I can say that PETER was about the most difficult and complicated showsI have ever staged. Fair warning to all taking it on, PETER is a "play with music" to the same extent that WEST SIDE STORY or CHORUS LINE are "musicals with dance".
The tricky part is that while the cast only sings three full numbers (and two other very short ones), the score is over 100 pages long and there is critical underscoring and musical effects in every scene. Make sure you get a good musical director and a lift / fight director. Also make sure your cast is fit, healthy, and game for lots of physical work what with moving trunks, leaping from one character to another, throwing boys, running in place and very little time off-stage to catch your breath. Everyone in our cast wore knee pads in rehearsal and performance. Lots of trips to the chiropracter also. That said, it is also one of the most rewarding shows I've worked on.