One note on Johnny Rockets - the history of surcharges is interesting.

Originally, when Voyager launched, there was a charge, and it was quickly removed.

For a few years, Johnny Rockets was free on all 5 Voyager Class ships. The result of this was that kids filled the place whenever it was open. They'd set up shop in there, order burgers, fries, etc and stay there eating all day (and often ordering something, taking one bite, then ordering something else.) As a result, there were long waits for the rest of the passengers, many of whom never bothered to eat there because of the wait and all the kids.

The $3.95 service charge really cut down on the kids using Johnny Rockets as their hangout instead of Adventure Ocean. Also, all Crown and Anchor members (Gold, Platinum, and Diamond) get a coupon for one free meal at Johnny Rockets. (Also, the $3.95 gets you all the food you can eat while you're there.)

As for mustering, almost all passengers muster on outside decks, not in contained indoor areas. I've been on 6 cruises, and have never seen a partial muster drill. (Although, as was mentioned, passengers and crew do not muster at the same time.) In fact, every cruise I've been on has seen a full lifeboat drill on one side of the ship in at least one port.