My dogs love Hide and seek also!
Some of their other favorites are:
-Clam shell/cups game: 3 identical cups with a treat under one. Allow your dog to sniff it out and tip over a cup to find the treat.
-Which hand? (the person who showed me called it "Houdini Hound"): hold out both fists. A treat in one, and the other empty. Your dog sniffs and then gently places a paw on the hand they want to open. This game really builds on several commands including "sit", "find it", and "paw" (my command for touching something with a paw.)
-Go get it- Hiding treats in various locations for the dogs to sniff out and find.
There are others..... I'll probably be back with a few more later!