A really good question is whether the Big Goal(s) should encompass the entire organization, or just focus on one or two departments. In my Silicon Valley experience, I found that goals shared by the whole company were much more fun and effective.
Personal example: in the mid-80s, Hewlett-Packard focused the entire international company on improving the reliability of our electronic instruments by a factor of 10. Many of us were skeptical at first, but we did it. That accomplishment truly brought out the best in the whole corporation.
I think setting out a Big Goal is one of the best, most energizing things you can do to move your company forward. If you decide to do it, keep these three dimensions in mind. That will be one more factor that will help you succeed.