I built our titleblocks into the project template as elements. Then, I created sheet templates (in the "standards" directory) that xref in the titleblock element(s).
That way when you start a new project, you have everything built in ready to go. If you end up with 30x42 vs 24x36 you just switch the sheet template. Or, if you have various sizes you can set the sheet template for each subset.
But, the main idea is that everything is already there for the user. It's not the same as having an auto-sizing titleblock, but it is as good as it gets.