We have been on other Carnival Caribbean cruises, usually 7 day or short 4 day cruises. We chose this cruise because it was going through the Panama Canal in August. This is unusual, but they were repositioning the ship from Tampa to Australia. We went from Tampa to Long Beach, CA.
We really enjoyed the ship. Though it has over 2000 people, we never experienced a crowd. The layout was easy. The kitchen galley is on the lower level, below the dining room, and not between two dining rooms like on other ships. So you can easily walk from the front to the back of the ship without having to go up or down a level. The "Serenity" area is large and a relaxing spot to sit back and read a book or do nothing. There are two pool slides, one where you sit and one where you stand and they drop the floor out from under you. Both were fun.
We alternated between eating lunches at the lido buffet and the dining room. The selection at the buffet was good, but didn't vary too much. The Chinese station and the Deli station would back up during the lunch hour.
I chose this category (1st floor, outside window) because when you return from shore excursions, you can easily walk up one flight of stairs to your cabin instead of waiting for an elevator. This usually works very well for us. On this cruise, we were traveling quite a distance and were traveling 22 knots/hour through some rough seas. Occasionally, we would hear a loud crashing noise, like a metal pipe being dropped. It was a large wave hitting against the side of the ship. It woke us up a few nights. In this case, a room on a higher level may have been the better choice. Another thing to be aware of: Right above this floor is the theater, casino, lobby, etc...so there is quite a bit of foot traffic right above you, expecially on the starboard (right) side.