I think the kids would definitely love all those things you mentioned and when I think about it we went to Disneyland Paris for our last holiday which we enjoyed but wouldn't go back as it was so stressful. So busy and fast paced, up early every morning and out till late at night. We needed a holiday when we came back to recover!
Had thought a canal break would give the right balance of rest and play as we could sort of please ourselves on the pace.
Life jackets would definitely be worn at all times, even by myself just in case, also sets a good example to the kids anyway. Think I'm swinging more towards just going for it as at the moment we are all really keen but as the kids get older I'm worried they'd lose interest and we'd end up not doing it at all.