Just 10 minutes from the venue, you can always arrive early and stop by the falls on the way to the ceremony. They are a beautiful little corner of Washington State and they are just a 3 minute walk from the parking lot. Keep in mind parking is busy on summer weekends so only swing by the falls if you have at least 45-60+ minutes to enjoy the experience.
This place is a must stopover if you're doing any touristy spots while you're in town. It's right next to Pike Place Market and the crumpets simply cannot be beat. Green Eggs and Ham, Lemon Curd, Ricotta with Honey and Walnuts, or even just a simple Nutella crumpet will give you day a big WIN!
This is a great spot to view Seattle from Queen Anne Hill. It's just above downtown and overlooks the Sound and city with Puget Sound in the background.
If you have a fun afternoon in Seattle, walking on to the Bainbridge Island Ferry is a great way to get on the water (it's only a 20-30 min crossing). You can hop off and stroll the 1 main block of cute shops and restaurants on the other side, or just turn around and head back to Seattle. It's Nat's favorite view of the city as you head back into Seattle.