Just curious -- were there specific activities or events that your boys enjoyed? We were on Fantasy in January, and DS(6, almost 7) did not like the clubs at all. In fact, he disliked them so much that he asked if he could have a babysitter instead of going!
I would wonder what he didn't like, and why? Do you still have the Navigator, and would he be able to remember the activities he didn't like if you went through it with him?
My son likes "anyone can cook", GAGA ball *sometimes* (he prefers the way Royal plays it, but I cannot tell you anything more because I have NO clue what gagaball is in the first place), Get the Hook, some Stitch adventure thing. He has, in the past, liked the arranged times for dancing on the light up floor on Dream, but the last two cruises he hasn't wanted to do that. Which is weird, since he's a dancer and he has LOVED the attention he gets from allll the girls when he's the only boy dancing with them. (it's possible it's that very attention that is getting to him, as he's getting older and it probably embarrasses him)
He would have been 8 for his first
Disney cruise and now he's 10.5, so he IS older than your boy, but those things are what he has enjoyed.
It tends to be very important to show up as early as possible on the first evening, to get to know the counselors, get to know what's going on, etc. I'm not sure that club/lab kids really make friends with the strangers there, but they get to recognize each other, which makes them feel like they belong. If you don't go until the 2nd day you can feel left out (I've heard this gets to be stronger as they go to Edge). And if you go to the ones that have multiple steps, like the Stitch thing and especially Get the Hook, then you really feel part of something bigger.
Now with the Navigator app for smartphones, you can look up every day's Navigator and see when the next scheduled time for something is. So I was able to set aside the times for Get the Hook for DS, on our first evening. That time was taken, because he enjoys doing the entire thing. He usually likes Anyone Can Cook, so I set those times aside in our schedule as well, but after the first one he didn't want to do it. (he said that it was taken over by the kids on the Club side, and the counselor really pandered (my word not his) to the little ones and so DS felt talked down to and it really
really irritated him...he didn't want that to happen again so he didn't want to do it a second time on our most recent sailing) Knowing when things will happen, and if they will happen again, is so terrific for making sure kids don't miss something they like (or so you know when NOT to send them if it's something they really didn't enjoy).