First, try to get over your shyness. DO STUFF. Talk to people, get on the stage when you have a chance. Cruises are great places to meet and talk to others and when the cruise is over it's done unless you made such a good friend you keep in touch. And while I usually have a big enough crowd to command my own dinning table the few cruises that we shared a table hold some of my best memories. A table for just the 2 of you is not necessarily the best thing. You can do that anywhere.
A thought about Atlantis. I thought it was a bust. unless you take a tour that include the aquarium you have to pay extra (like $40) to get in. We asked some folks there and they said it was not worth $40. So unless you want to gamble it was a waste. I think you can gamble on the ship if that is your style, at least you can on Carnival.