Other opinions I have:

Excursions are super expensive when booked through the cruise line, but are probably worthwhile if this is your first cruise. There are cheaper alternatives if you're an experienced traveler.

I dont recommend Carnival unless you don't mind public intoxication and possible Walmart-like behavior from fellow cruise goers.

Seated/Main dining for dinner is fun.

Window cabins are superior to interior cabins and a better value than rooms with a balcony.

Book a year out for best prices and best options.