Flymia

Post above is spot on for food. South Beach is worth seeing, but I would not make an entire day out of it. Think of South Beach (Ocean Drive) as our Times Square. Something everyone needs to see but don't focus on it. It is very touristy, and over priced. If you have a car makes a big difference how much you may want to do. Also depends where you are staying. Brickell is a nice area as well for the evening, and that is where I would suggest you go for before or after dinner for drinks. Sugar rooftop bar in Brickell City Centre is one best views you can get. Unfortunately, Miami lacks many good rooftop locations.

Plenty of beach areas that are not filled up. North of Lauderdale or even south on Hallandale Beach will be fine. Remember all the beaches are public, even the beaches in front of $40,000,000 homes on Golden Beach are public beaches. No spring breakers there, just need to get a ride (rental car or uber) to the beach access points. Unless you want the beach with walking to and from restaurants and bars, those areas would be busy. Only other negative is more traffic and some higher hotel prices.

It is decent, but certainly more of a tourist area. Few locals go there. I can't really recommend anything as I have not been there often other than walking through. Brickell City Centre is a nice spot, with much better dinning options. Not on the water though. I would suggest maybe lunch at Bayside, and dinner at Brickell City Centre, or anywhere around the Brickell area.

This is Miami. Your requirements are hundreds of hotels. Arriving in the late afternoon there is no reason for a place inside the hotel. Just book something in Brickell or Downtown and chose the endless amount of places to eat dinner in the area.

United does not have a big operation in Miami compared to other airports, so there is no club. In the 1990s and early 2000s they had a small hub in MIA, but those days are long gone. Not sure if they have any partner clubs as there are other clubs in that terminal.

Uber/Lyft. Both drives are not long in mileage, time will vary based on traffic, but very short rides in mileage.

There is zero reason book anything from hotel to port. It is a 10-min drive, just do the Ubers. Airport to Hotel, I guess you would save a little bit a money. But given the reviews, I would not do it. The savings are not huge and there is not a huge hassle to just get two Uber XL. Miami Airport is close to Downtown, just traffic makes the drive longer sometimes.

I would recommend spending some time on Las Ollas if staying in Lauderdale area. For seafood in Lauderdale I go to 15th Street Fisheries. Just remember when you are eating seafood in Florida, get the fish that actually live in Florida like snapper and mahi. Don't order salmon. If you don't mind driving Garcia's has great fresh seafood, it is also a seafood market right on the Miami River. Not a view, but the river is a working river where some of the fish comes in. From there you could take a quick drive to Brickell and check out Brickell area and Brickell City Centre. If you want to see Miami that would be my plan.

Larry Limo is highly recommended. Though depending on how many people/bags you have may not be needed. It is not a long trip.

It varies but you are looking at very early morning, before sunrise. Almost all the ships are docked before the sun comes up. 4:30 a.m. to 6:00 a.m. is when they come in. There are some pretty good videos online you can see here: https://www.youtube.com/@BLCStreams

You could stick with the upper Keys, give Key Largo a look. About 90-min drive from Miami. It could be a long day trip or spend a night there. It is not as famous as Key West, but still the Keys with great scenery and water. But that is definitely a water/beach type of trip. And by beach small beaches, not resort type beaches. Key West has more things to do in town lots of history etc.. I would say you would need two more days to really be able to enjoy the keys and take that trip. Miami has changed in 10-years and certainly plenty of things to do and see. A rental car helps a lot.

With luggage I just don't know if it is worth it. 3pm flight means getting to MIA by 1:00 p.m. If you don't have TSA Pre the lines can get long on a weekend or in the evenings on any day of the week. I would just get off the ship as late as possible and head to the airport. Hopefully you are flying out of North Terminal or South Terminal (most airlines use these but a few like Southwest, Frontier and Spirit use the older terminals). North and South have a lot of options to sit and relax, have a decent lunch and even walk around some shops.

Not Miami, but in November we took a 3-night to Bahamas our of Port Everglades, and Customs getting off was nothing. Took maybe 30-seconds. I don't even remembering giving them my passports, just walk through a line that said passports instead of birth certificates. No lines, no wait.

6 people how many bags? May as well just take two ubers and be done with it. Its 20-30 minute drive.

The book a refundable hotel and keep looking is the best advice. This far out in December is going to be high, and if lots of people book it will remain high. But chances are sometime in say July or August you will find better deals.