Hi Graham, here's what I see for July in the Seattle area. Unfortunately, it's a pretty meager schedule for July in 2014 (there's good stuff in June and August, though).
June 29th: Classic/Long style event at Salmon La Sac. It's not in July, but if you can come in late June, this is one of the top areas in Washington State (US Middle Champs in 2009), about a 2-hour drive east of Seattle. I wish I could guarantee that this event will be held 5 months in advance, but the Forest Service is notoriously slow in granting permits (we always apply ASAP in October, and get confirmation about 2 weeks before the event).
July 16th: Wilburton Hill. A small weeknight event in a city park. Like a sprint, but not on a sprint map. It'll be a CascadeOC event this year, but no link yet.
July 19th: 4-hour or 8-hour rogaine at Tiger Mountain. I'm not aware of an event being here before. It's on the west side of the Cascade Mountains, so the woods will be lush and green!
July 27th: Union Bay Paddle-O. This CascadeOC event is in the city, just south of the University of Washington, and there's a canoe rental place on-site. In years past, it's been a freestyle event (get 5 or 8 checkpoints in any order you want, but no time limit). But the course designer mentioned that he may increase the size and scope of the event this year, so we'll see.
Usually, there's been the annual Seattle Night & Day Challenge (16-hour urban rogaine), but it's taking a break in 2014. And there aren't any Street Scrambles (the 3-hour versions) in July. There aren't any
'Hood Hunts on the calendar (yet), but you can download any of the old maps and do them whenever you want. I can't guarantee all of the trivia checkpoints will still be there, but it's free, and you can get a feel of the Seattle neighborhoods.
Also, if you're in for a gimmick, check out a
Thursday Adventure Run, put on by a local running store. It's a 60-minute publicity stunt that's essentially an urban rogaine. It's free and you can win stuff. There'll be on on July 3rd in a hip area of Seattle, and another (I think) on July 17th around a shopping mall in the suburb of Kent.
Also, if there's a chance you'll be here August 1-3, the Canadian Champs (S/M/L) will be in Whistler, BC, which is about a 4-5 hour drive north of here, and will be excellent.