How the money works
Cruise lines sell most suites through advisors and pay them from the fare. The fare is the same. Booking direct does not make it cheaper. It just means nobody is on your side when something changes.
Advisors sometimes have access to group rates and added amenities the public site does not show. I pass those on.
What you get that the website does not give you
Someone who has stayed in the suite category you are asking about. A cabin number picked on purpose. A human to call when the itinerary changes or a hurricane moves the ship.
One person for the cruise, the hotel the night before and the car to the port.
Fees
I do not charge a planning fee for cruises. If that ever changes for a complex multi-part trip, I say so before any work starts.
What the website cannot do
A cruise line's website will sell you the suite that is left. It will not tell you that the cabin two doors down is quieter, that the sailing a week later has a better itinerary for the same money, or that the drinks package you are about to add is already inside the suite fare.
It also cannot pick up the phone when a hurricane turns the ship around. I can, and I have.
When booking direct is fine
A three-night Bahamas run in an inside cabin, booked a week out. There is nothing to plan and nothing to protect. For anything with a suite, a group, or a flight attached, the advice is free and it pays for itself the first time something changes.