I have help in my gardens and one of those people is my lawn maintenance guy. I hired him years ago when we moved into our SJC home because he was willing to listen to everything I wanted (only organic methods, no weed spraying, etc). When we removed large sections of lawn in the back yard to put in flower beds I ended up leaving grass paths, mainly for my dogs that have a hard time on gravel, my second option. I was always looking for some kind of edging to keep the grass out of the beds, but never found one that I liked enough to incorporate. My maintenance guy edged the beds monthly with a weed-wacker and a few months ago I noticed that the beds were getting bigger and the grassy paths were getting narrower. He was taking out a little bit of grass every time and it was starting to show.
So it finally forced me to deal with my edgy problem and I am now adding my favorite edging, boxwoods. We then added fresh compost and grass seed to the bare dirt edges and hopefully they will grow back to the edges of the boxwood and the paths will be the ideal size again - wide enough for two people to walk side-by-side through the garden!