Take a look at the pavers that are kinda like lattice work; criss-cross pattern concrete with holes about 3"x3". The work pretty well in some places and still let grass grow in the square holes. If you set them deep enough you can still mow across them without flinching too.
This shows them, but we used to get them pretty cheap at an ornamental concrete place.
http://www.belgard.com/products/pavers/turfstone
Home Depot may have them too.