Coco Nara is expensive but is considered to be some of the best coals available to hookahs.
Other than that. Please keep in mind that big places not often is very comfortable, and a hookah lounge shouldent be a 280 seating lounge. It should be very inspired by baduins and their camps. Round seating places, tbl in the middel, sitting on big puffs or relaxing chouches..
Good luck with it, im going with the idea to start one up in Denmark