I would concentrate on getting all the Continental Airlines miles you can before its merger with United. See my post of 7/1/11 on the What's New page of my website below to see how to go about doing this. Then I would cancel any Continental Airlines card you have just before the merger, then wait for the best United Airlines card offer after the merger in order to get another bonus. Both are Star Alliance carriers. That alliance should have no trouble getting you to Vietnam or most anywhere else in the world.