It is nice of you to take on the roll of a "travel agent" friend, but there is a reason professional travel agents receive commissions. They spend years learning about cruise lines, ships, itineraries, etc. full-time.
What is the 101 of cruising? I have been cruising for more than fifty years, and I have seen many changes, so the industry is never static. I never watch Youtubers or influencers--they just represent one small personal opinion, and usually the person is rarely as well traveled as I am.
Trying to figure out peoples' styles (formal or casual), interests (beach or city), likes (ships with waterslides or dance floors), budgets (inside cabin or suite), health (bus tour or walks on shore), etc. is a LOT of work. Different cruise lines can better appeal to diverse people in many ways!!
Okay, saying you will then search out the ideal cruise in a specific month means an even more exhausting amount of time spent looking and comparing.
Also, just looking for a "deal" on some website somewhere opens you up to scams, poor service, weak communication and follow up, and so forth.
I NEVER answer this type of question for people--that is what I call grunt work, and why should I do it for someone when he/she can consult a professional travel agent? Members of AAA usually receive free travel agent services.
However, just to get a big picture, you can plug in all your requests here on cruiseline.com FIND A CRUISE, see what comes up, and then start reading the reviews of all of the different cruises and ships. Currently the cheapest cruise lines out of Florida are probably MSC, Carnival, and NCL, but sometimes you can find bargains on other cruise lines if the ship is not full. American holiday cruises (Thanksgiving, Christmas, New Year's) are usually more expensive than other weeks. Check to see what the cost per night is--sometimes longer cruises can be more of a bargain if they really want to sell the cabin.
Best wishes, and I hope you get to cruise as well--not just your friends. Bon voyage!