(Updated 8/2015) Looking for stars in Seattle? The further you can get from streetlights, the better. Darkness is what you need for the best stargazing.* If you’d like to join other astronomy enthusiasts, try one of these local events!
Good City Parks:
Solstice Park : West Seattle – 7400 Fauntleroy Way SW in Seattle : This city park is open from 4am-11:30pm (as of June 2010) and has good views from south southwest to north northwest and a very open sky. The eastern horizon is blocked to about 35 degrees up. You have to stay back from the edge of the overlook to avoid being overpowered by the tennis court lights, but the trails themselves are relatively open and completely unlit. Official website 
Green Lake Park: North Seattle – 7201 E Green Lake Dr. N : Green Lake has the distinct advantage of being open 24 hours, but there is more lighting on the trails, and it is more centrally located within the city, so cutting off skyglow can be difficult. Official website 
Lincoln Park:  Go down to the water and you’ll have all the view you could want to the West. This park closes at 11:30pm.
Don Armeni Boat Ramp : (North-facing) There are more lights in your face than south of Myrtle Reservoir.
4am-11:30pm is one of the standard sets of operating hours for Seattle parks. Here’s the February 2009 Operating Hours proposal , which has some explanations of why.
Favorite Non-Park In-City Locations:
Myrtle Reservoir : on SW Myrtle Street between 35th Ave SW and 36th Ave SW. Stand between the water towers outside the fences, and you’ll have a full view of the Northern sky.
Sunset Ave SW & SW Seattle St : (North-facing) is an intersection overlooking a bluff. This is not a public park, be respectful of the neighbors. View is Northwest
Other parks I plan to check out “this year” (I wrote that so many years ago…):
Jefferson Park : a re-developed park on Beacon Hill, great views to the west from the trail around the sports field. Below the Park on the west side is a grassy slope along 15th Ave. S between S. Spokane St. and S. Dakota St.
Sunset Hill Park : 7531 34th Ave NW, 98117. Ballard area, great western horizon I hear. Starting at 7001 East Green Lake Way N Seattle, WA:
1. Head northeast on East Green Lake Way N toward NE Ravenna Blvd 0.8 mi
2. Slight right onto Green Lake Dr N 0.2 mi
3. Slight left onto N 80th St 2.7 mi
4. Turn left onto 32nd Ave NW 0.3 mi
5. Take the 2nd right onto NW 75th St 0.1 mi
6. Turn right onto 34th Ave NW
Destination will be on the left 98 ft
I’m looking for more 24-hour parks in Seattle, so far I’ve found:
Atlantic City Boat Ramp, 8702 Seward Park Ave. S
Green Lake Park, 7201 E Green Lake Dr. N
Kerry Park (Franklin Place), 211 W Highland Dr.
Myrtle Edwards Park, 3130 Alaskan Way W
Stan Sayres Memorial Park, 3808 Lake Washington Blvd. S
Eddie Vine Boat Ramp, 8001 Seaview Ave. NW
Wallingford Steps, Wallingford Ave. N Street End at N 34th St.
Sunnyside Ave N Boat Ramp, 2301 NE Northlake Way
Let me know what you think of the stargazing at these sites. The boat ramps are usually only open 24-hours if you have a permit and a trailer.
Star Parties and Observatories:
The Seattle Astronomical Society hosts stargazing parties in two locations in Seattle. http://www.seattleastro.org 
Green Lake Star Party: Green Lake star parties are on the north shore at a grassy area west of the Bathhouse Theater, near the fishing piers on the lake.
Paramount Park Star Party: The park address is NE 155th and 8th NE in Shoreline.
The University of Washington Observatory has two open houses each month. Look through the UW’s 110-year-old refracting telescope, and listen to a short talk. The observatory is located in the northwest corner of the campus. http://www.astro.washington.edu/groups/outreach/tjo/ 
The Battle Point Astronomical Association on Bainbridge Island has a number of star parties and observatory open houses. http://www.bpastro.org 
Getting out of the city makes for even better views of the sky. Here are some of my favorite stargazing locations within a few hours of Seattle. Most of these are fee-based public areas.
Campground on Lake Kachess: In the Cascades just off I-90. The boat ramp has a good view towards the Northeast (perfect for Perseid viewing). Be sure to talk to the ranger beforehand though, the boat ramp is in the “Day Use Only” section of the park. Info: www.reserveamerica.com 
Lake Ozette in Olympic National Park: Near the tip of the Olympic Peninsula, has a good reputation. Stay near the water (out of the trees) for the best sights. Info: www.nps.gov , Brochure , Campground 
Bowman Bay Campground: The Boeing Employee’s Astronomical Society recommends Bowman Bay Campground in Deception Pass State Park on Whidbey Island. Info: www.parks.wa.gov 
Staircase Campground: My favorite stargazing location, Staircase Campground in Olympic National Park. When you get there, sit on the bridge for the best open-sky views. Info: www.nps.gov , Brochure 
The Perseid Meteor Shower
If you spend any time stargazing this summer, be sure not to miss the Perseid meteor shower.
General dates: July 20-something – August 20-something, after midnight
General peak: Usually August 11, 12, or 13, 12am-3am
To see the Perseids, turn to face the constellation Perseus, which will be rising in the Northeast a bit before midnight during the month of August.
*Please use caution walking in the city in the dark. I recommend using the dimmest red flashlight that allows you to see trip hazards when stargazing. Also, be aware that many of Seattle’s Parks close at 11:30pm.