I'm going to try to write this with tons of information that I know I'd appreciate.
** before cruise, purchase plastic luggage tag holders through Amazon.com. You will be thankful you did.
First, when you get to Miami, check in at the Carnival Counter at the airport. Even before this, you should have done all your checking in online. Have your boarding passes and passports in hand when arriving. We were checked in in only a few minutes and got our room keys. You'll appreciate this when you arrive at the port and see the long line of people waiting to check in. At the airport your boarding pass will get stamped with Airport Check-In and you can skip the line at the port. You will just need to show them your room keys and give them your health questionnaire. Once we arrived at the port, which was around 1pm, we were on the boat within 10 minutes tops.
If given the option to have any suite or a cove balcony, I'd take the cove balcony every time. Great room, quiet location and very private balcony. A little snug for 4 people but not a deal-breaker. Closet space was better than other cruise lines. Bathroom was great. Suited our needs with plenty of counter space and shelving.