Do you have any houseplants?
Before I started taping my snakes' sweater boxes down securely, I had a couple escape, and both times I found them coiled up in the water pan (the one you put under a plant to catch any excess water) underneath a potted houseplant. I think they must be drawn to the smell of damp dirt. If you have any houseplants, I'd check those out first. If you don't have one in the room where the snake escaped, try putting one in there and checking it periodically.
Liz