Running a business certainly can not be separated from the purpose of doing business is to achieve profit. In an effort to achieve profit, have you had a good marketing plan? Or it turns out your business is running in place without any clear management.
Who should see your plan? All the players in the company. Firms typically keep their marketing plans very, very private for one of two very different reasons: Either they're too skimpy and management would be embarrassed to have them see the light of day, or they're solid and packed with information . . . which would make them extremely valuable to the competition.