September 20 is Park(ing) Day in Seattle, when a parking space can be turned into a mini-park for about six hours, 9am–3pm. Applications are due on Friday, August 30! Look at this link for more details. http://www.seattle.gov/transportation/seattleparkingday.htm
Perhaps there is interest out there to participate in this park making event. The event raises awareness about important issues like creating a walkable, livable, healthy city. You can do almost anything as long as you turn in a plan, (rough sketch) and get a permit by Friday.
The city website as lots of creative ideas for parks done in the past. Have fun with it.