Don’t ignore the nice trails off of I 90 like rattlesnake ridge twin falls snoqualmie falls, snow lake and the like. Also highly recommend checking out deception pass corner bay and the north beach. The shrimp shack is an amazing place to get food.

Also Discovery park is really near Seattle and has a great trail and beach.

Also are you gonna get burned out from physical exertion from hiking multiple days unless you are used to this type of physical exertion?