I would not feel comfortable in casual clothes on formal nights on any Celebrity ship............Wilba.
Alaska is an American state and thus it's currency is US Dollars. Canadian dollars will be needed in Vancouver and if touring in Canada rather than Alaska. Read the reviews. Americans tend to dress up on formal nights much less than the British and there have been complaints in reviews about this. Definitely take warm clothing! Layers. Rainwear. Stout shoes. They do not have all those glaciers from having a tropical climate! Imagine you are going to Scotland.