sod would be nice, but you would need an irrigation line to keep it lush looking.

OR, use a good quality artificial grass.

I also like a herringbone brick pattern

the gravel looks better w/a paver driveway

but, you could do something like this, with a good polymeric sand to hold it in place. or maybe something like the pebble tech w/epoxy coating.

I've also seen succulents used (if you're in a harsh winter zone,,forget it!)

large mexican pebble tiles are also an option

(you could set them in mortar)

or leave them like this. make sure you go deep enough.

Thank you both for the great feedback (and photos!).

I should have included our location in my original comment. We’re in the California Bay Area so nothing weather related that we need to worry about (although water rates are crazy so less watering is usually a good thing).

That grass looks so nice when it’s well cared for though...

Hmmm... decisions!

I never did like those kind of driveways. Grass struggles to look good with car heat and oil/antifreeze killing the grass. Plants the same as grass. Brick does shift/sink and gets weeds in between. Gravel gets kicked up on the driveway and also weeds. I would hire a concrete contractor to lay concrete in the strip. If you wanted you could have it dyed and stamped like stone or brick for interest.

can you fill it in with a third row of cement?

I would use exposed aggregate. Or flowering thyme if you are diligent in picking out any weeds.

if using brick, lay down a thin base of cement first. Once cured, lay your bricks on that base. it will keep weeds out and the bricks won't sink and shift. the guy who wanted to do my brick pathway advised me of the correct way.

As for the grass, artificial turf requires no water and will always look green. you just have to get plusher type so that it doesn't look so fake.

I have a ribbon driveway also, with grass in the middle. I have to say I'm waiting on the budget to allow me to pave the whole thing. It doubles the amount of edging, I have to cut that strip which takes two passes, and I don't water it so the grass looks horrible.

My neighbor has rocks in hers, which are also now scattered into her lawn.

I'll be following this post for sure!