Did a little poking around last night. For a 3 night Caribbean in September 2022, it's $1685 for inside, $1727 oceanview, $1817 Verandah, and $3287 concierge. It leaves not far from where we live, so there's no airfare or hotel to worry about.
It's a more or less a no-brainer to go from inside to verandah. The question is if concierge is worth almost double. Again, this will be 100% on points - and for a special event, so I'm happy to splurge if it makes sense. Even with the concierge room, we'll have plenty of points for the nice dinner, the drinks, the excursions or whatever.
It's also very little extra for a 4 night. That would typically be an obvious move, but two factors come into play: 1. Our dog is getting old. The more days we leave her, the more stressed (and likely ill) she will get. Three days is already stretching it, IMO. Hopefully that will not be a moot point by then.
2. DH is concerned about seasickness. He has gotten it before, including on a small boat in the Keys where I was fine. I understand you don't feel the movement very much on these big cruise ships, but you never know. If he's a mess, why extend another day. (This may also be a reason to reconsider the inside room.) This is our starter cruise, we can always do a massive one a year or two later if this one goes well.
But my main question right now - is concierge worth it?