Road Trip from SF to Vancouver/Seattle- where are the best places to see?

Elliott, this is such a good idea! I hope you have a great trip.

Last June, I drove from San Diego to Seattle. I stopped off in San Francisco as one of my nights, and drove most of the Pacific Coast Highway (the US1/US101). Here's what I did:

• I drove out of San Francisco to Point Reyes National Seashore, and visited the Point Reyes Lighthouse Visitor Information Center. Interestingly, this area is super cool as it's where the San Andreas fault comes in from the sea to land.
  

• I had lunch in Marshall at Nicks Cove.
• I carried on north to Fort Bragg and the Glass Beach there.
  

• I visited the Drive-Thru Tree Park in the heart of the Redwood National Park.
  
• I stayed a night in Crescent City.
  
• I then turned inland, but if I'd had more time, I would have carried on north up the coast to Haystack Rock and Seaside (Oregon) -- the former being a beautiful rock out at sea, the latter a seaside resort town with a beautiful beach.
  

• Drive over the impressive and terrifying Astoria Megler Bridge.
  
• Visit Cape Disappointment State Park.
  
• If you want to spend the time, drive up into Olympic National Park and visit Port Angeles and Ruby Beach before turning back south to come through Seattle on your way north.
  

Have a good drive!

I haven't done that trip, but it sounds fantastic..just bring warm clothing. Here's a must visit place along the way for you to check out at Point Reyes 

Vancouver has as many things to do as Seattle.  It's a beautiful city.  If you want to see the mountains, that is the place to start.  After taking in all Vancouver has to offer you can head up to Whistler.  Or, alternatively, you can go from Seattle through the San Juan Islands and over to Victoria.  It will pretty much depend on where you fly out of.  Be sure to check the regulations for driving a rental over the boarder.  If you go to Victoria, you can leave the car in Seattle, take the ferry to the San Juans and then a ferry to Victoria.

Of course you MUST do Yosemite and Tahoe.  Make a note of "Glacer Point" and be sure and go up there when you're in Yosemite.  Most people miss it because they just stick to the Valley.  Their loss!