I would maybe think about taking more rest or relax time in between each national park, that’s a lot of hiking (we have a lot of steep hikes around here) and driving (we also have a lot of summer traffic). Also, in my opinion, N Cascades and Bham are an easier drive from the peninsula than doing Rainier first. Since Rainier is closer to SeaTac than N Cascades, I would think about switching those two.