I've been amazed at how much washer fluid I've gone through since moving to CO (get caught in ski traffic on i70 on a bad weekend and you'll probably use a quart). Luckily I have a fairly big fluid tank, and remember to check it often enough. Biggest problem I usually have is the rear wiper will freeze and not make any contact with the glass.

As for carrying a spare wiper, that is one of the nice things about having 3 windshield wipers that are all the same length (FJ cruiser). Something happens to one, you still have 2, which will clear enough of the window to have a good view.