Next May I want to visit these 3 Cities,all for the 1st time ..Can spend 7 days in total ,and looking for culture and outdoor events .. Advice please ( UK tourist !) JH

Which city will you fly to and from?
Will you have seven full days and six nights?

HTtY

The choice of arrival and departure city depends on the optimum trip .Can fly from UK to all 3 cities ..

Unless there is something you really want to do in Portland like drive the Columbia River Gorge, with 7 days for the whole trip you might consider skipping it.

Vancouver-Seattle with perhaps a stop in Victoria makes more sense to me, shorter distances and less moving around. You could easily fill a week between those two cities, especially for a first time visit.

Curiousgeo is right....too much for 7 days. Best do Seattle and then Vancouver. Tons to see/do in Vancouver....Seattle is worth 2 or 3 days. I like Portland but not enough in my opinion to take time away from the other two choices.

I agree. A better experience would be Seattle, Vancouver, Victoria, and a day trip to Mt. Rainier on a clear day.

HTtY

My suggestion for what it's worth: Fly to Portland and rent a car (morning landing if possible).
Drive east on I-84 and see Multnomah Falls (Oregons tallest) and maybe a couple other waterfalls. Spend a night in Hood River.
Drive back to PDX in the morning and turn in the rental car. take the TriMet light rail into the city and have lunch.
Take one of the Amtrak Cascades trains north to Seattle (about 4 hours). Spend 2-3 days in Seattle before taking an Amtrak train or bus to Vancouver for the rest of your trip.