From my past experience, I found that I spent the most cash on food. The groups I rolled with went out to eat for every meal and we had a blast. If that isn't your speed, don't sweat it, but Seattle has some great cuisine and I know I'll likely be looking to get some grub at some nice locations. Also, make sure to check the weather forecast in Seattle before going. Last year it wound up being pretty comfortable, but being that it is right at the end of August it likely stands a chance of being a bit muggy and you know, it could rain.