I'm not a clean freak, REALLY!

I'm going to share one of my frequent complaints. How in the world do you impress into your children the joy of a clean living space? You see, when the youngest in the family is a 17-month old who is constantly looking for new ways to get into trouble, the mess is a major hazard!
I've tried so many different techniques. Dire punishment for a room that is not made tidy within x amount of time. A reward for a room made tidy in x amount of time. Loss of toys/priviledges/timely dinner if room is not tidy. "Don't you know that it is much easier if you put things away when you are done with them instead of waiting until the piles are so big that you have to hurdle over them to get from one side of the room to the other?!". Each day I probably clean up half of their mess for them out of sheer exhaustion over trying to get them to do it. At least twice weekly I am tempted to empty out half of what they have and give it away. Bi-monthly I am already getting in there and purging what hasn't been played with in six months.
What is left is played with but maybe they don't need enough dishes and plates for our whole neighborhood. Maybe they don't need 20 animals and baby dolls. Quite possibly 10 is enough. I've put a moratorium on any new toys. 90% of their artwork is admired for a day and then sent to decorate the recycle bin. Polly Pocket is EVIL and must be destroyed - -ha ha ha (said in a sinister voice). No really. Whoever thought a tiny doll with parts you could accidentally inhale and choke on has a sick sense of humor. Any Polly parts left on the floor are fair game for the broom and the vacuum cleaner. I've invested in lots of storage containers and rearranged for the best flow and play space.
Seriously though. When your girls happily (or mostly happily) play together, using their imaginations, and don't whine every ten minutes saying "I'm bored", it is hard to get super upset about the mess. The problem is the mess still has to be cleaned up and they'd rather do anything but clean. So, how to motivate? That is my question today (and almost everyday!).