SticktoPriest, your grandparents are likely not insane. It seems they agreed with the majority of theatergoers (including me) who found SITPWG dreadfully boring onstage. Those of us "very involved" with theater know that in order to truly enjoy a Sondheim show, you must be familiar with the score, prior to seeing the show.
Many people fall in love with Sondheim shows via the recordings and kind of "romanticize" this love of the recording into a great respect for the actual stagework too.
I don't know too many people who love Sondheim's work as much as I do. However, I learned many years ago to use great caution in recommending anyone see a Sondheim show without first being VERY familiar with the score.
Every show Sondheim has done since GYPSY and WEST SIDE STORY is very difficult to appreciate, absorb and ENJOY upon first viewing.
I wish you or someone had recommended that your grandparents not see SITPWG without first being familiar with the OCR.
Had they been familiar with the score, they likely would have loved the show when they saw it.
Quite simply, this is why virtually every Sondheim show is a financial failure on Broadway.
Sondheim's glory and genius seem best shown and best appreciated on recording or when presented in revue format such as PUTTING IT TOGETHER or SIDE BY SIDE BY SONDHEIM, etc.
Again, I love Sondheim's work with a great passion. But, I am aware it is unwise to suggest one of his works to a "casual theatergoer" or to someone unwilling to invest the time in learning about the work and listening to a recording of the work.
Many people have treated opera in this fashion for many years. They know those opera scores and librettos by heart, and this is often the KEY to them enjoying what they are about to see live onstage.
Sondheim's work is best when approached in this "operalike" fashion, or in the aforementioned revue format.
If you can get your grandparents to listen to the SITPWG cd a few times.........it is likely they would fall in love with the show and be delighted to see live again someday, or on the video made of the original production they saw. :)
"MAY YOUR LIFE BE AS BRIGHT AS BROADWAY AT NIGHT"