Portland and Vancouver were absolutely the right choices for the two new MLS expansion teams. St. Louis, Ottawa and even a return to Miami had been discussed but Portland and Vancouver were more deserving over all three of these cities.
Portland and Vancouver have paid there dues in USL for a long time now and have created quite a Northwest rivalry alongside Seattle so with the Sounders getting a franchise, these two cities were the logical choices.
St Louis may feel hard done by but i don't believe it would have been fair for it to get an expansion over two sides that had auditioned for long enough at the USL level.
Portland and Vancouver will help create a great rivalry with Seattle in the Northwest and we will start to see an atmosphere that is really only seen at Toronto games and with the Chivas/Galaxy rivalry. 
We should also start to see away fans at games with Portland, Vancouver, and Seattle in such close proximity and that will create an even better atmosphere throughout the league.
I have been lucky enough to play in the Northwest and the fans are some of the best in the country. Seattle fans showed what an atmosphere they can create in their home opener and my prediction is Portland and Vancouver fans will rise to the challenge and at least match it when they play their first MLS game in 2011.