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.
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.