It has been awhile since I was at Atlantis (2001) but you can eat reasonably at the tiki hut on the grounds by the pools and at a place called the Atlas Cafe or Grill or something along those lines near the casino. This assumes both places still exist!

Let me know how your stay was and what you ended up doing. Food/excursions/etc. Thanks and have fun. I had a blast the one day we were there. Took hours to pick the wedgy out after taking a trip down the shark water slide....... But sooo worth it.