For all of the main story quests, you should get the next quest after the previous one. The two biggest ones I can think of that would be easy to miss are talking to Bowlord Lewin in the back room of the Archer's Guild (Since you talk to an NPC to go to his room, the main quest won't appear on the map) just after the big fight with the gargoyle, or back in Ul'dah after visiting the three nations.