My mom just sent me these photos of her visit to the High Line in New York City, a brand-new park created out of an abandoned elevated train line that will be 1-1/2 miles long when fully complete. A gardener, she especially noticed the plants, which were carefully selected to look like weeds and planted in natural groupings as if they had just sprung up. With its views of the city and artful landscaping, the park was wildly successful from the moment it opened. It is so popular they have to limit how many people can go up on it. There are many stunning photos on the website.
I really love this plant selection (and the whole concept of making a destination park out of an abandoned track) and I had a sudden revelation that this is what I want to do in our front yard: plants that look like weeds, but aren't! And some old railroad tracks! I wonder if my husband will go along.