The Lotus Casino in Vegas is very tricky in getting children to stay there forever, forgetting the rest of the world. In
Percy Jackson: The Lightning Thief, Grover, Annabeth, and Percy fall under this spell with a certain delicacy, the Lotus flower. This flower numbs and dulls the senses to a point where your mind is no longer registering the responsibilities of the real world. This seems to be the perfect trap for this purpose.
However, I think it would be even more useful to enchant the doors. The doors should be one-way, along with no windows to look out of. You could walk in, but never walk back out except for certain people, such as gods and the owners. Doing this, even if anyone broke the charm, there would be no way to leave and no escape.
Another helpful suggestion would be to keep out any adults. As adults would be dangerous. The lotus flower may not be strong enough to dull a grown human's senses. If the adult found out and was concerned, they could rescue the children and get the Lotus Casino shut down.
