I've traveled with an iPad, a 6+ and a Touch. I rationalized it that I only needed one charger...
My first excursion, so equipped was with my iPad 4. I didn't touch it once. Played games, and read on the plane, listened to music on the Touch.
My second excursion was with an iPad mini instead, and I did use it a little more, but only to save my 6+ battery for when I arrived, using Touch for music.
Third, shorter excursion was 6+ and Touch. Slimming down I guess. Played games on the Touch while listening to tunes and an audiobook I ripped from CD's.
A cruise is more about the places you go while on a cruse. Worrying about iPads and stuff is just more worry.
PLUS if you are flying on one of the notorious 'RJ's', every added item means it has to be slogged down the aisle, stuffed into a bin, argued over with the FA on whether it will fit or not, and lugging it around under watchful eyes of airport thieves. Oh, not to mention the clueless 'security theatre' dancers that still occasionally want me to remove the iPad from my carry-on apparently 'just because'.
Oh, and the time when a security theatre dancer 'called my bag' because I had 'a lot of stuff in it' and they couldn't make out what was in it on the x-ray screen. That was a nice touch to an already arduous travel day...
Although, reading comment 26, I have to say that I was glad I had my iPad on a cruise that was supposed to spend the day in 'Lovely Grand Cayman', but when it got there, it was too rough to let anyone out, so we stayed anchored far off shore. I spent the time reading a 'book' on my iPad. It *does* come in handy...
Oh, and another thing on cruising with technology in general: Power outlets. They have gotten better, but...
On a recent cruise, the room had plenty of outlets. Schuko outlets. There was only ONE 'standard' US outlet making it harder to charge things, and use hair dryers, and whatever. Consider that. The Apple International Power Adapter set is great, just sayin'...