we have stayed in a cat 1 on both the wonder (3-day) and magic (7-day). the wonder cat 1 we got just a couple weeks before we sailed...our TA (only time we went thru a TA because i wanted the
AAA pin set) called to tell us that the walt suite was open if we wanted it. since we had 2 cat 4s at that point, and the suite was only another $650, we took it. frankly, i wouldn't do that again...for the amount of time on the 3-day (or the 4-day, for that matter) that you are in your stateroom, i just don't think it is worth the money.
we sailed on the 3/9 magic cruise, again in the walt suite. we booked a 2 br for that cruise in nov 2000 and got a call from our reservationist at
dcl (who has booked every one of our cruises except the nov one) who told us she saw the walt suite open up and she put us in there.
we booked our next 7-day just last week for may 24, 2003, but the best available at the moment is a 1br. debbie knows to keep her eyes open for either a 2 br or one of the royals for us. a lot can happen in a year, so we're not too disappointed as yet.
all that to say, yes, it can take a year or more's advance planning to get a royal suite, but then again, things happen in people's lives that cause them to have to cancel. if you REALLY want a royal suite, call your TA and ask to be on the wait list for a cat 1.
to answer your other questions...what was it like? WONDERFUL! you have so much room, you can separate yourselves from the kids, you can put the kids to bed and still watch tv (even in the master bathroom, if you want), you can get a hot breakfast from room service and enjoy it on your veranda, you get free soda and water (plus assorted other goodies throughout the cruise), you have someone call you before you ever leave home to schedule your excursions, your palo's brunch and/or dinners, your wine tasting, etc., you have lots of jealous fellow cruisers who want a peek at your stateroom

, but most of all, you just feel pampered!
would i do it again? IN A HEARTBEAT

but only on the 7-day.