Besides the obvious tablet, pens, bible, shampoo, and stuff the hotel leaves there; why not plant a few odd items. Like an egg in the plant, or a particular soda in a bathtub filled with ice. On the other hand, maybe you should check with the hotel to see if they allow young girls running around a hotel room looking for items. They may even let you use an empty conference room.

if it's the hotel room your family has rented, the hotel desk won't care. If it involves the hallways, etc., they will.

You could have them look for something in the Yellow Pages. Once you get there, you could add items visible from the windows (a neon "W" from the car dealership across the street, for example).

hangers, iron,