I think some cruisers feel obligated to see 'the big show' and then sit there bored for the whole time, not willing to admit they'd be having more fun sitting in the karaoke bar. "It's a Broadway production, we HAVE to see it!" Well, I am among those who didn't care for either Hairspray or Chicago. It's not that the performers were bad - they were excellent - it's just that I didn't care for the story lines and songs. Technically they were great productions, but neither one 'reached' me if you know what I mean.
I'm looking forward to Mamma Mia though, because ABBA music can get everyone in the audience caught up in the musical. Same thing with Saturday Night Fever. They offer something familiar to most people.