Agree with Toto, a cab or a water taxi ride is worth the ride to the Atlantis. If you want to see the "Dig" , you can purchase a ticket for about $25. If you don't want to see the "Dig", you can still walk around the grounds and the hotel/casino.
In order to get to the pool area and grounds, you must go thru the casino. And they will never refuse anyone from the casino area.
Just did that tour in July. You must see the aquarium (dig). Might be pricey, but glad we did it. Lunch & beach chairs, and water taxi were included. Only problem was that my husband and son had enough sun and headed back to the ship early. That particular tour, you can't catch the water taxi until 3:00. I asked them why didn't they get a cab.