Hi Kat! I took my two kids (3.10 and 4.5) on the Grandeur of the Seas last January and they had a ball! I was also in charge of planning a surprise cruise for my husband's birthday so I was trying to balance itineraries with ship size, golf excursion availability and also consider the kids.
The younger one was disappointed that they wouldn't let him in (age limit was 4 years but I think they have a new playgroup-Mommy-N-Me type program now for 18m-4y) but we just brought playdough with lots of kitchen tools and lots of coloring books. He still talks about the playdough and several other "little" kids came over to join us, too. The older one had a ball in the kids program!! He couldn't wait to go every day and we DRAGGED him back to the room at 10 pm every night, protesting that he wanted to go back and wasn't tired while his eyelids drooped! One night, they dressed and made up the kids to be pirates and they paraded through the dining room (late seating) and had their pictures taken. For the rest of the cruise, other adults would see my son and say, "Aren't you one of the pirates we saw the other night? Boy you were a fierce-looking pirate!" He was in seventh heaven every time.
This was my first time cruising with kids and my first time on RCCL (previously only on NCL cruises) so I am not sure if the kids helped identify us or what, but I thought the staff was very attentive to both us and the kids. Do watch out for the video games next to the kids program entrance, though. We are telling our kids they have to save the money to play them for the next cruise.
ONE WARNING: I discovered this little fact thanks to this chat group: children who are not potty trained AND/OR with swim diapers are NOT allowed in the pool. When I emailed RCCL they confirmed this, stating that there are plaques beside all of their pools stating this. When I responded with a request for them to point this out to me in their brochure (I am not on the ship yet, people!), they never responded. However, I noticed that the very next issuance of their brochures had this "little detail" in it.