Certainly lots of room there for choice.
I'd enter Yellowstone via Red Lodge, MT. This road takes you over Beartooth Pass, a road that Charles Kuralt called "the most beautiful road in America". Check first, this pass is 11K feet high and sometimes doesn't open until June. This year was a very low snow year, so you may be in luck. If it is closed, enter Yellowstone via Dead Indian Summit and the Chief Joseph highway.
I'd leave the Tetons at Jackson via Teton Pass, (WY 22 and ID 33 and 31) via Victor, ID. I second Vladimir's recommendation to pass through Craters of the Moon NM on US 20 between Arco and Carey, ID. Then follow US 20 to Mountain Home, ID, joining I-84. There to Portland will be a bit of a grind along I-84, relieved by the Columbia Gorge, east of Portland. If you traverse the gorge in the afternoon, be prepared for very strong headwinds.
From Olympic NP, I'd cross to Vancouver Island at Port Angeles, Visit Victoria if you have a few hours (the ferry from the US docks right downtown) then cross Georgia Strait from Swartz Bay to Vancouver. That gives you two lovely boat rides instead of more dreary Interstate from Seattle to Vancouver. If you time your second ferry ride to be at or near sunset, you'll have some excellent photo opportunities.
This is important: Exit Vancouver to the north, rather than to the east. It's a bit nasty through Vancouver, but Stanley Park and the Lions Gate Bridge will make the slow going through town worth it. A once-around loop through Stanley Park is worth it, too, even if you don't get out of your car. Then take BC 99 exiting the Lower Mainland via Squamish, Whistler, Lillooet and Cache Creek. That drive is about three and a half stops more scenic and interesting than the horrid, busy Trans Canada east out of Vancouver via Chilliwack and Hope. The highway traverses a dozen or so climate zones and offers spectacular scenery from end to end. allow about half a day for this if you don't stop. But stop you will.
You link back to the Trans Canada via Cache Creek at Kamloops and then it's a straight run to Jasper and Banff. Moraine Lake near Lake Louise is a must-see if you're a Canadian, it was on the ten dollar bill for years. All of the Banff Jasper area is camera heaven. Just be aware that in the national parks, you can't camp anywhere except the designated campgrounds. The various towns, however (Banff, Canmore) are fair game. Stealth is important.
Good shooting!
Peter
