You keep it "in place" by constantly trimming it. I hope this doesn't insult you, but the varieties of mulch and all the separation make the beds look much too busy. The rocks especially must be a nightmare to keep clean of leaves and other organic debris.

I don't have rocks, that's was just an inspiration image. So far the bed the just bare soil so I have options, should I just do the creeping thyme?

I would use the creeping thyme, yes, but I wouldn't trim it to such a severe edge. The naturally spreading look is much more aesthetically pleasing IMO. Just go in a couple of times a year and pull out any that is creeping too far to suit you.

"The rocks especially must be a nightmare to keep clean of leaves and other organic debris."

I have rock mulch in my rock garden and just blow it out every time I mow when I blow off the sidewalks, driveway, and porches. Not a big deal.

But I do agree that the area in the photo is looking much too sterile and regimented.

sunshine home, my creeping thyme is creeping all over the stepping stones in the center there. It's a really vigorous grower.

I found creeping thyme too invasive. I use Veronica pectinata and Veronica prostrata instead.

I have 4 or 5 different creeping thymes, and yes they need to be controlled. The Veronicas plantswoman suggests just were too weak growers for me. Colorado and WV--very different conditions.