Open Jaws

Mary, yes it is possible, and it is on most airline sites. They don't call it "open jaws" ,which is how I know we all refer to it though.
Instead of clicking on "one way" or "round trip" you just click on " multi city".
Just enter your flights and go. I have been doing the same( searching for open jaw flights) for the last two weeks and have been on many airline sites, they all call it either " milti city" or "multi destination".
Good luck.

Generally, "open jaw" means flying into one city and returning from another but what you want to do is legitimate. However, you might want to check one of the multi-carrier sites (kayak, Orbitz, travelocity, etc.) as often such deals are best done on multiple carriers. AS someone suggested, use the "multi-city" option.

John's right...use Kayak or Booking Buddy, or some of the sites he's suggested to get the best prices. you CAN do it on the Northwest site, but it will only offer you flights on Northwest or its partner airline, KLM...not always the cheapest.

Kayak is not the be all end all, at least not for Canadains. We have a low cost airline , ZOOM , which Kayak does not pull prices on. It is a well established and well known airline here with excellant prices to London,Paris, and a few other Europeon destinations.
Anyone considering flying out of Vancouver for instance , should really look at Zoom, their premium economy( just more leg room) prices are often better then regular ecomomy on many airlines.

Air Canadas price for me to fly open jaw into Rome and out of Paris were almost 500 dollars higher then Zooms.

But if she wants to fly back to Portland, Zoom isn't much good. Many discount airlines aren't listed on these search engines because their timetables aren't accessible by search engines....They don't pay agents for sales of their tickets, so it's not worth the search engines' efforts to integrate the information for free. While Zoom's prices are good, to me, their premium economy wasn't worth the extra $$...and I'm 6'2". And I don't think I'd call them an "established" airline....they've been around less than six years and fly four aircraft.

Mary, there are a couple of options for arranging the trip you mentioned. Flying out of Vancouver is good, as it will probably be a direct flight (possibly with a brief stop in Calgary). For the return trip, you could either find an airline with a direct Amsterdam-Portland route, or return to Vancouver and use Horizon or Air Canada to Portland. You'll have to decide which is the most acceptable solution for you.

Considering cost and the fact that AMS-PDX flights usually transit AT LEAST one other airport (Dulles,Chicago,Heathrow or whatever), I suspect the AMS-YVR-PDX route is going to be the most cost effective for both time and money.

I've use Zoom in the past and found the service to be great. I've used both economy and premium seating, and found both to be good. Whether the expedited check-in, slightly better leg room, "free" booze and other perks is worth the extra cost is a matter of personal opinion. If my budget can handle it, I usually choose premium.

Happy travels!