Right...
I'll jump in with an old riddle (but still quite good) or two, then a comment on the levers question from Merak
Riddle#1: Picture a bedroom with two beds, two dressers, two of everything, even two young girls fish bowls. Speaking of young girls, Sally and Jane lay dead on the beds. Both died of drowning, yet there are no marks of struggle, and the beds are quite dry. How did they die??
Riddle#2: John was found hanging 5 feet off the floor from a rope tied around the rafters of a 20 foot high ceiling in a concrete floored warehouse. There's a large spreading pool of water below him. He's quite dead, and there's quite literally nothing else in the warehouse. How did he die?
Like I said - oldies, but goodies

Oh yeah - one more:
Riddle #3: Eddie and Aaron are dead in a cabin in the woods. It's over 500 miles to the nearest living being, and no on else was here when they died. If they didn't kill each other and didn't die from natural causes, nor other animals, what killed them?
As for the levers question:
It doesn't matter how you arrange the rooms, really. All you have to do is identify 9 levers with 3 states each. 1-A, 1-B, 1-C; 2-A, 2-B, 2-C; etc.
For every pair of levers, you have 6 distinct possibilities of configurations. Assign each single lever to two, non-adjacent, portals and put all the portals (doors, portcullises, etc.) in a straight line... Embed some levers in between doors for some extra fun.
Now divide the levers as follows:
1 & 2 is one pair, 3&4 is the second, 6&7 the third, 8&9 the fourth. Number 5 is by itself and controls 3 doors.
1&2 control doors A&B, 3&4 control B&C, 6&7 control C&D, 8&9 control D&E, 5 controls A,C, and E.
Place the doors in a randomly determined open/close pattern. Neglect to tell players how many doors there are, or what each lever does - only tell them precisely what they see/hear (doors opening/closing etc.)
Stand back and wait for the howls of anguish as they -slowly- work their way through it.
Alternatively, try this one on for size:
6 levers on the wall, six rooms. Each room is shaped like a D6, with round, open holes connecting to the next room. Each wall contains the same number of holes as a corresponding D6. Each lever on the wall connects to a single room and rotates the room in 2 dimensions. The goal is to find a configuration wherein the holes in the walls line up with holes in the wall of the next room...
Just don't tell them it's a d6 room

Erase holes on the ceiling and floor to hide it better. Also, you can add 3 positions to each lever - the first position rotates the room to the right, the second to the left, and the third switches the roof with the floor (an engineering marvel to be sure)
For more fun with either variation, included teleportation traps that are moved by the levers, that teleport the players back to start. Make one such trap be a total 'reset' of all the doors/rooms.