https://www.talkofthevillages.com/sm...ic,2284.0.html
https://www.talkofthevillages.com/sm...ic,2112.0.html
those two threads are worth a read. we plan to do the same thing in time.
I think the rock color might depend on your tastes and villa color. Our villa is tan and we're likely going to put some of the darker red lava rock up close to the villa for contrast, and perhaps a bit of river rock on the fringe, but this is just some far out planning. good luck.