I've done a Panama Canal transit on the Miracle (2019) from Tampa to LA, a 13-day cruise with only three ports (not counting the PC day). Older demographic - check. I think we had less than 20 under the age of 18 on our sailing. Fewer lines for certain things were very noticeable. Make sure you plan accordingly when sailing through the locks. You will want to see more, and people gather early to get good seating. It also takes much longer than expected to make it through all of the locks; we miss the tail end of the locks to get dinner. Journey cruises generally have a throwback evening, so watch the schedule for that. Overall, it was a very relaxing cruise with a lot of downtime to catch up on sleep.