I knew it looked familiar!
Things are expensive. We ended up staying at the Comfort Suites which is right next to Atlantis and has full privileges. We brought a rolling cooler, and made lunches to bring over to the water park/beaches. The kids meals are pretty reasonable. There's a man-made cove you can snorkel in which has ocean access and we saw turtles and some other cool fishies in there. We did a different dolphin encounter which was pretty cool. There's a ferry which goes from near Atlantis (short walk to pier under the bridge) to the cruise ship terminal in Nassau if you wanna do some shopping. Note that the lazy river at Atlantis is not all that lazy, and the sides are pretty rough so be careful. Daughter enjoyed getting her hair braided on the beach.
Warning - we had our credit card skimmed somewhere (we think at the Hard Rock). Use cash as much as possible.