I've got over 400 hours put into this game, and I'm now on my second playthrough, and in neither of them have I been able to become Thane of Solitude. I've done the quest for Elsif, both Wolf Queen quests, have been able to purchase Proudspire Manor, and have done numerous quests to help the people of Solitide. Some of the Solitude guards even occasionally call my character Thane. Yet I get no dialog option from Elsif offering the title of Thane, or even any option to ask her if she has any other tasks to perform. I have no housecarl, so I didn't get the title and forget about it.

Do I have to do something like join the legion first?

Edited: Forgot to mention, this is on the PC, v1.8.