I have the Shipmate app, and though it is a third party app, it is very well constructed with lots of information, tools, and tips. If you have a group going (as I do with our wedding) then you can list everyone's cabin number in the app, and it has shorcuts to the deck plan so you can see where everyone is. It also has information on all the excursions, restaurants, and stores. It has deck plans, tips and information. I thought it was all very neat.
Yes, I said neat.
Good luck to you all,