We sailed on the Coral Princess (sister ship of the Island) to the P Canal a few years ago, and were on the Island to Hawaii last year. Both are beautiful ships.
We loved the Panama Canal cruise. Read as much as you can about the Canal before you go, so the transit will be more meaningful. It's an amazing experience.
I don't know if your cruise is a full or partial transit. Ours was a partial from FLL. But we were able to make it into a full transit by takng the "Ocean-to-Ocean" excursion. That's a bit pricy but well worth every penny, because, as I said, it makes a partial into a full transit.
Did you know you can see ships (cruise and cargo) going through the locks on a website called cruisediva dot com. Go to the home page, look on the left side of the page for the site map. Clicking on that will bring you to another page, and there you scroll down on the right side of the page to the listing for port and ship webcams. Click on that listing and there will be a page with a list of webcams. Choose the post cams. Click on the one for the Panama Canal. It loads kind of slowly, but on it you can view the Miraflores Locks (western), the Gatun Locks (eastern), and the middle of the canal with the Bridge of the Americas in the background.
I still emjoy watching the ships traveling through the Canal.