I'm hoping to at least have some basics for the "Tourist Highway" area, which is directly downtown and a part of the old Pioneer Square area (Or directly adjacent to it).
The Tourist Highway is a major part of the "Public" Underground. It runs between the two most commonly mentioned public entrances to the OU, Lordstrung's and the Big Rhino. Conveniently enough, there is now the Seattle Transit Tunnel. WHich runs directly under Lordstrungs and then between there and the RHino. So we've co-opted a major portion of that for the Tourist Highway.
There's a few other locations that we've defined (and have marked on the map) that are popping up in Missions.
Dunno yet what we're doing for maps or anything... I don;t think we'll have a "Definitive Map" of the OU... We want to leave a lot open for the GM to play with... And a lot of the connecting tunnels are simply random, winding mazes, so it's easy to get lost if you don't know the tunnels, even if you know approximately which direction your target location is. And the tunnels are collapsing and being redug, moved, etc all the time. All part of the charm.

SRM 04-00
Back in Business, the first Missions adventure, has a map of the Lordstrung's Entrance to the OU/Tourist Highway though. It also covers one of the other major "areas" we've set up for the OU... Pirate's Cove.
Bull