Can you tell us a little more about your area - sunny or shady, dry/average/moist, size, city/rural setting, etc. Are you thinking of starting with seeds or plants?
Here's one thread to ponder about when starting a wildflower garden:
I think your idea will work very well, but it is more work than most people think to get it going. After the first year though, it really will cut down on the maintenance and will be a very pleasant view.
Age is a biological fact.
Old is a state of mind.
I will age, but I refuse to get old.