We have used Brightline Train to travel between Miami and Fort Lauderdale. Liked it very much.
We had an issue with cell reception at the a port of Miami; ended up with a taxi to the Miami Central train station instead of rideshare. The trains and stations are new, clean, with friendly staff.
Brightline has options between their stations and hotels - this is evolving, adding more options, as they build out their business.
For hotel in Miami after arriving at that airport, I stayed at a Courtyard in LeJeune Road. They had free hotel shuttle from the airport; shared with the Marriott and the Residence Inn at the same campus - each had its own swimming pool.
They offered port shuttle, about $12.50 pp OW, but it required sign-up. I used Lyft, at a time convenient to me. For more than one person, it is a better price.
We stayed at the Hampton Inn in Brickell Downtown; no shuttle, but a nice, walkable area of new development. Close to Publix, Dunkin, Starbucks, many restaurants. I think Disney’s hotel partner is in the neighborhood. Again, we chose rideshare.
Many people recommend the Blue Lagoon area, south of the airport. If you want a free hotel shuttle, I would check out the Marriott campus or the hotels in the a blue Lagoon.
We stayed on Ft Lauderdale visit after arriving (post Miami cruise) at the aft Lauderdale Station. They transported us to our hotel.
I expect to pay for a shuttle from hotel to cruise port. But most are close and can be reached with rideshare (or paid, often booked with hotel front desk).
Dania Beach area in Fort Lauderdale is popular with cruisers. But it’s not a beachfront hotel area.