Although the half marathon has thousands of runners, the full marathon has about 1500. It's a local race on a beautiful course, historic.
The first half has some significant hills coming to the express lanes and the ends of the I-90 bridge. This may not be relevant in the future since the course will change because of light rail construction. Miles 18-23 have substantial extended and rolling hills. Weather is very variable in late November, be prepared for sub-freezing weather, driving rain, sun, but most likley overcast with drizzle.
My running club, the Seattle Green Lake Running Group, provides the official pacers, and they are the nicest and most reliable pacers anywhere!
By WSDW about 2016
Very well organized on the course. Lots of friendly volunteers along the route and plenty of rehydration stops. Lots of portable toilets. Pretty and challenging course. Good running conditions in 2016. Nice finish.
Recovery center was pretty lame. Warm but food/drink limited to water, bananas, dole fruit cups, cheap mini bagels with nothing to go in them, Darigold milk based protein drink, and believe it or not Folgers coffee packets (this is Seattle). The organizers should meet up with the Cascade Bike club (the organizers of the STP) to learn out how they look after participants at the rest stops
Not much fun walking up and down steps of Memorial Stadium to recover gear check - gear check could easily have fit into the recovery center building.
Expo okay but hard to find a volunteer who knows anything about the race.
If you are running the marathon get there late after the half marathon crowds leave. Street parking is pretty easy a few blocks west of the Seattle center. Start does not use corrals which it just about gets away with.
By SG about 2016
The course was very pretty and I really enjoyed the atmosphere but the hills were much steeper than I had expected. They were small but steep!
I would certainly recommend running the first half slower than you want to because the hills on the second half of the course are brutal.