We're planning to drive from Wisconsin to Seattle next summer and are looking for the "must sees" across the top of the country and in the Seattle/Vancouver regions. I'm geographically challenged so I'm not sure how many days to plan assuming we take three days out for national parks. I've heard Yosemite is wall to wall traffic in the summer, are there better alternatives? What's the best way across the divide, through Boise? We'll fly back from Seattle if we can swing the cost. Your expertise is much appreciated.