Roadtrip from Washington to San Francisco

Hi Guys,

I’m from Argentina and I’m planning a road trip to the US with 2/3 friends. Our idea was to rent a motor home and start our journey up north, getting to know the two major cities Seattle and San Francisco, using them as starting and ending point. We want to explore and enjoy the American natural beauty, including Yellowstone park, the national Glacier park, and other points of interest you may recommend.

We will be doing it for 15 days, and I want recommendations for vehicle rents, camping, points of interest, and wich season is the best to make this kind of road trip.

Any ideas/ recommendations for how to start planning this trip? I will really appreciate if you already planned something like this and you share your experience with us!