Try using Orbitz.com or Kayak.com and choose multi-segment/multi-city flights. You should be able to add a hotel option somewhere within the process.
I think the problem you're running into is the flight from Seattle to Hamburg beceause there probably are no direct flights. You'll have to stop in Frankfurt then take a plane or a train ride. I already looked and if you want to fly from Frankfurt to Hamburg, it's going to cost a pretty penny on that one segment alone, not to mention, a huge waste of time. Start considering other options like the train.
For trains in Germany -
Banh.de
My suggested route: SEA-FRA-HAM (or take the train) - FRA-YVR
The airlines that fly from Frankfurt and Hamburg is Lufthansa. I don't know the dates you're flying but it seems like July 1 - 9 from FRA-HAM on a return flight is as low as $188CDN tax in. Not bad if you're pressed for time and have a big budget.
What you can do (just a suggestion) is you can fly on Air Berlin/LTU out of Vancouver direct to Hamburg.