It seems that now you have to basically plan out every activity/meal reservation on the ship prior to the trip and hope some activities weren't booked.
When Royal Caribbean introduced the
Oasis-class ships, what you describe became an issue; instead of one main evening show with 2 performances to accommodate early & late seating dinner crowds, several different shows would run daily, and given the large number of passengers, having people schedule in advance became needful. That said, I'm told you can often show up for stand by status at a show without a reservation, and since reservations are free many people who reserved don't show, so you've still got a good chance of getting in.
On Royal, I've sailed
Voyager,
Freedom and
Oasis-class. With the
Oasis-class, you get Central Park and the Boardwalk neighborhoods, and more variety of shows and specialty restaurants, plus 2 flow riders (I don't recall what all the others have now). Onboard water park offerings vary;
Harmony of the Seas (
Oasis class),
Liberty of the Seas (
Freedom class) &
Adventure of the Seas (
Voyager class) at least have water slides. The
Oasis-class are so huge they're very limited in what ports they can hit, and 2 I used tend to hit 3 islands/week-long cruise.
Adventure of the Seas on the other hand might hit 5, and the southern Caribbean route I found more interesting.
I've not sailed R.C.'s
Quantum-class. I recommend Cruise Critic's forum for researching cruises. Just like here, there are repetitive debates - get ready for multi-page online combat over dress code adherence, and debates about whether young children or entitled elderly are the most obnoxious.
Richard.
P.S.: I think of a cruise as an appetizer-sampler of varied destinations I might want to come back to someday. You don't get to do a lot, but you can figure out Bonaire is arid and scrubby, St. Lucia very lush, the ocean around St. Maarten & Barbados gorgeous, etc...