I personally like the civil war quest line, I only did it from the Legion perspective though, I don't know how it is for the Stormcloaks :shrug: I also enjoyed the main questline but I agree, not my favorite MQ from the Elder Scrolls series, Morrowind gets that honor from me. I guess you could just devote yourself to exploring all the dungeons, seeing as there are so many it might keep you busy for a while, some even have quests attached but if you refuse to try the other guilds I can't help you.
Edit: I don't know how far you are with the Companions but you should try going through with them, the story gets interesting later on.