If you find the bar missions boring then you are flying the wrong ship. Try a ship that is a couple weapon classes lower, or go find better missions. The mission difficulty should be about ship class times 5, i.e. 15 for Starflier, 30 for Anubis and so on. Naturally, it is near impossible to find challenging missions for any ship that is bigger than the Falcon.
Besides, you haven't finished SP until you reached level 38
- in a VHF (teaches you making money fast, up to 2 million/hour)
- in a light fighter (teaches you fighting)
- in the Humpback (teaches you trading and turret fighting)
Try beating the campaign with different kinds of ships - heavy fighters, light fighters, freighters - and see how far you can take the Starflier (mine is still sitting in Kyoto
). See the thread
Level 7 for info on how to fly SP missions back-to-back without wasting time on freelancing.