Didn't mean to single anyone out. I just found that on the cruise talking to other mommies of 3-4yr olds at the pool - the general conversation the first two days included "how's the oceaneers club and have you put your child there yet". There was a lot of hesitation leaving the child there to have some adult alone time. That just surprised me I agree every child is different, that's why a recommend before booking the excursion take the first day to test the waters, get them use to the place and drop them off at the club for the time you will be gone on an excursion. If it works, then book it. We waited until day 2 of our cruise to book the excursion, had no problems, there was still plenty of openings.
Another good time to put them in for those a little hesitatn is in the afternoons, around11-12, after they come back from lunch it's quiet time (3-4yr olds). They have mats, pillows and blankets and get to watch a movie on the big screen. This is usually exciting for most kids-so if you know it's nap time, you could schedule an afternoon excursion, drop em off and at least hope they sleep;-).
Just an idea