We went on our first cruise last year with our our two year old. We asked the genie to arrange in room sitting each evening and he was adamant that we should use the nursery. I was very hesitant but decided to give it a try. Wow-was I impressed!!! I dropped him off before our dinner with his pj's. When we returned, they had played with him, fed him a "late night snack", changed him, rocked him and then put him in our stroller to sleep. When we returned, I wheeled him to our room and transferred to the pack n play. It was the easiest night out ever!!!
After that, we used almost every night and he happily went in. The staff become familiar to him. They were incredible and much cheaper than a sitter at home. They even put him in his sleep sack!!
I would highly recommend a Maclaren stroller. They are small and very comfortable. We got the one that reclines so it was great for getting him back to the room. Good luck!!