Thank you all for your responses. They confirm my thinking - I should go ahead and move it.
CL, I never considered that there might be someone on the waiting list for our departure. That would be nice if we could open up spots for someone else.
Frank II, I thought the same - I am the customer. Not sure why I dithered over it.
Carol, it is a Royal Caribbean cruise. Transatlantic from Miami to Amsterdam. My biggest fear has always been being met in Amsterdam by people in hazmat suits because of a big outbreak on board, and being sent straight to quarantine instead of our planned two weeks post-cruise in Europe. And a smaller fear that the protocols will change again, and our Canadian vaccine cocktail and schedule will leave us to be considered "unvaccinated", and as such relegated to the unvaxxed venues on the ship. I'm not paying to be held in specific areas of the ship with the truly unvaccinated.
Pam, I could just about take both in terms of vacation entitlement at work, but DH has five fewer days. Its a moot point, we simply can't afford both. The RS tour is in US$, we are Canadian, so its quite expensive. Luckily we put together a very last minute trip to France in October, so aren't feeling the gap between trips as intensely as some!
Judy, the tour we chose is Best of Turkey, and there's a good amount of availability left on a number of departures. I wish when we booked I had thought through it further and just gone for the Monday departure. It was a fast decision to book. DH never had interest, and then suddenly he agreed. I booked as fast as I could before he changed his mind.
The good news is Royal Caribbean has just extended Cruise with Confidence, so we can move our cruise to one departing by April 29, 2023, without any penalties. I will suggest that to my sister. She won't want to incur another cent on this because her booking was made with cruise credit from a cruise in March 2020 - one of those with literally no notice of cancellation, so she lost some money on airfares, etc. We can also move it to any departure past that for $100pp penalty. Sis is in Florida until the 30th, and Royal releases 2023 itineraries on the week of December 6th.
Thanks again, everyone! I will report back.