Yep, finding a snake that has escaped can be very difficult. I'd also suggest putting a rolled up towell at the base of doors that lead out of your home in order to block the snake's exit.

Here's a twist on Stefan's suggestion. You might prepare a few containers of worms, and put them in the middle of a flat cardboard box with flour on it. Then lay block the gap under doors with towells. If the snake comes to investigate the worm smell, it would leave tracks in whichever room it's in. I actually found an escaped snake in a cold room with it's chin resting on a container of worms, so I know it can work. I didn't use the flour trick, though.