Based on your requirements I would suggest; painted concrete! That is my usual suggestion to anyone who wants to grow living plants under lousy condions & with no maintenance needed. It is an impossible request.

More kindly, I would definitely say NO to the idea of seed. Any of the weeds already growing in this area will have seeded in the soil. As seedlings you will be unable to tell the difference between the plants you want & those you don't.

Really, if you don't want to do any work, an inorganic solution would probably be the best. How about putting down a landscape fabric topped by mulch or river rock? If you still wanted plants you could put a holes in the fabric, improve the soil slightly in those spots & then plant a hardy tough grass. For the sunny spots Little Bluestem (Schizachyrium scoparium)might survive your conditions and would be trouble free for your neighbour. Shady dry spots are a little more difficult.......

good luck,
A.

Consider species Deschampsia cespitosa (tufted hairgrass) if you receive 35+ inches of rain or are willing to run inline emitter drip tubing. A beautiful cool season grass that also shows well into winter and only US$10/lb. For a pic of deschampsia in bloom see my blog for the grass in bloom early AM.
unofficialtaos.blogspot.com
Aug 04 2008

good luck