May not be the approach you are looking for. However my parents put down sheets of some kind of tarp or covering. Then they put gravel and stones all on top of that. The occasional weed shows up on top but not often, and they are easy to pull up out of the gravel. They cut holes in the covering to put plants in some areas (enough room for upper ground roots to breath also).
Or in several areas I have put down MANY layers of newspaper around the base of my plants. Then came back and topped that with mulch, and some leftover fishtank gravel.
I do know that the hot little stones are wonderful resting places for butterflies. If indeed you want to attract them.
"Somewhere in the yard, let fresh water accumulate to support communal "mudpuddling" so butterflies get soil salts and minerals as well as moisture. Finally, butterflies like some flat stones for basking or sunbathing, to gather warmth to power their wings".
http://www.urbanext.uiuc.edu/greenline/ ... 03.03.html