Thanks for all the advice, everyone. We had a great time!
Our butler, Edward, was amazing. He was very helpful, insisting we use his services. We had room service through him several times and weren't charged. He brought beers to the room so I could have a drink on the balcony whenever I fancied. They were charged for, obviously. My wife is happy with coffee but wasn't fussed on the pods supplied.
Both of us have mobility issues and found the ship large so didn't make it to the Epicurean every day, but breakfast there was peaceful (and delicious) with no screaming kids while we were there. More luck than judgment I expect as we saw lots of toddlers/pre-schoolers on board.
The whirlpool bath was lovely. My wife thinks it seems as strong as the deck jacuzzis but obviously not as deep. Our balcony overlooked the jacuzzis and we were a bit shocked to see people taking toddlers and young kids into them. We stuck with our 'private' jacuzzi after seeing that!
Our cabin steward came in as we were about to disembark and asked if we minded if he cleaned the bath while we were there - he filled it, put chemicals in then ran it. Reassuring if you have the heebie-jeebies about stuff like that (like my wife who remembers a hotel whirlpool bath that had clearly never been disinfected so had pools of black grot in the jets!)
We couldn't see any sign of priority check-in when we arrived at the terminal but as we used assistance I doubt we'd have come across it anyway. If you have mobility issues this service is rather special. A shout of thanks to the guys and gals (especially Bob) that man it. My wife was whisked through (though the wheelchair was wobbly so was a bit alarming at times) and very grateful as walking it would have worn her out and taken us ages.
So, thanks again for all the tips. We had a great time and are thinking of booking again.