The best place to hang signs in Seattle is this fence behind
Kobe Terrace Park. It's a quiet, peaceful place to work in plain view of some ten lanes of traffic, none of which have a hope of reaching it. My signs generally stay up here for about three days, passed by over 200,000 cars per day.
This fence over the 90 Westbound tunnel makes for a good dramatic posting spot, though signs don't stay up as long. Remember, signs go on the inside of the fence, not directly over traffic. Park on South Irving St. at Lake Washington Blvd.
This fence, outside the bike path between E. Roy St. and Bellevue Place, commands a fine view of both north and southbound 5. It's a bit scary to get to (hole in fence about ten paces south - look down...) but perfectly safe unless you're drunk or prone to sudden suicidal impulses.
A easier alternative is just to use the side fencing along the bike path (above.)
Cel tower fencing at Park and ride lot on 5th Ave. NE, just north of 130th/Roosevelt Way exit on the 5. Steps away from quiet, easy parking, good view of northbound 5.
(How to attach signs to fencing: Place cardboard against fence, strap some bungee cords across it, walk away.)
10th Ave. South at S. Weller just north of the 5/90 merge. Sign says "One Sign of Global Warming"
NE 59th St., just south of the Ravenna exit.
Bike Path off of Ripley Lane, next to I-405 southbound. Good view of northbound traffic, requiring miles of doubling back to reach.
Pedestrian walkways have very high visibility, but tend to come down quickly. If you really want to reach a lot of people, fencing along the sides of the freeways works best.
YTD - 388