I personally think more work equals more bonding for kids. Obviously, not too hard to discourage them, but enough that they feel a sense of ownership and have earned their skills. For this, I think kids in the 5-6 and up would benefit from having their own boats. Kayaks are really affordable and kids can personalize how they want (stickers, paint, etc.). I'd recommend one for each kid, because you know how possessive kids can be. If you want them to love it and stick with it, they really need their own boats.  For taking a couple small kids under 5, I actually would recommend an inflatable, as they can be bought at larger sizes and are "more comfortable" for kids who will just be along for the ride. Plus it has the same sensory effect as a bounce house or similar, so they will be immediately drawn to it. Last thing you want with a bunch of small kids is too much trouble getting going, so an inflatable can be tossed in the back of the car, blown up in minutes, and launched without any help.