There is a wide range of roofing options. Each differs in look, longevity and cost:
Cedar Shakes (approximate cost: $11-$19/ft²)
Composite (approximate cost: $4-$9/ft²)
Tile (approximate cost: $11-$20/ft² — note that weight of tile may require roof reinforcement)
Metal (approximate cost: $8-$19/ft²)
Green Roofs offer reduced stormwater runoff, added insulation and an interesting architectural element.
The addition of solar panels to your roof is an option you may wish to consider for electricity and waterheating. Even if you don’t have immediate plans for solar power, consider pre-wiring your home for future installation.
The US Department of Energy provides more helpful information on solar power, lighting and heating.
Additional roofing information:
King County Eco-Cool Remodel Tool: http://your.kingcounty.gov/solidwaste/ecoconsumer/eco-remodel.asp
City of Seattle Green Home Remodel Guide — Roofing www.seattle.gov/dpd/cms/groups/pan/@pan/@sustainableblding/documents/web_informational/dpds_007584.pdf