I would give the Paradise a try.
Her cruises are usually reasonably priced. She does 3 and 4 day (I believe) from Long Beach, California.
Even the "formal nights" are not formal on Carnival. You can pass with business casual every night (even "formal night") . Polo shirt and khakis or dress pants and a long sleeve shirt.
Besides the formal dining room, your cruise fare includes hamburgers, hot dogs, a buffet on Lido, 24 hour pizza. sushi during certain times of the day and 24 hour room service. (although a $1 tip for room service is pretty standard)
The only "food" thing has cost extra is soda and bottled water (but you can carry on your own), alcohol and speciality coffees/desserts on the Promenade.
If you are cruising as a single person, you will be hit by the "single penalty" since all rates are based on double occupancy.
The food is not 5 star, but you do get your money's worth.
Give it a try and see how you like it!!