Hi Youngcouple and welcome to the board! I have found that the age of passengers on the PG to be the youngest compared to the other ships in the fleet. We saw lots of honeymooner's, which this trip is perfect for!
I always make my excursions as soon as they open up online, if there is something that I really really want to do. As for dinner reservations, I usually only make them if I have plans to dine with a large group.