Saturday is National Cohousing Day in the U.S. A free tour in Oregon's Willamette Valley (click for details) starts at 10:30 AM at CoHo Ecovillage in Corvallis and continues at 3 PM at Oakleigh Meadow Cohousing in Eugene. The latter is still in process, here's a flyover rendering of their project. (At 5 PM back in Corvallis, CoHo Ecovillage will be showing the excellent documentary Within Reach at 5 PM, it's about a lengthy bike trek touring communities across the U.S.)
Cohousing hasn't (that I've seen) really cracked the hard nut of affordability, but they tend to have some very thoughtful takes on social & ecological design, and be hubs of interesting activity in their neighborhood/city/region. CoHo Ecovillage, as the name says, is on top of being cohousing an eco-village, another network of groups doing some interesting and often very well-grounded innovation. There are a number of other ecovillages in the area, including Maitreya in Eugene itself.