Out of 80 titles (I left out the "Historical Biography" category, which featured 4 queens, 1 king, and a virgin, on the grounds that it strayed toward nonfiction), titles that included the word:
Scotland or Highland: 11
Lord/Lady/Laird: 8 [This does not include Duke/Duchess(3), Courtesan(2), Queen(2), Marquess(1), Baron(1), Earl(1), or Knight(1)--including those would bring the total of nobility-based titles up to 19, or about 25% of the total]
Now, the Scotland count is a bit skewed, due to the "Scotland-Set Historical Romance" category, which consists of five novels, but still, I didn't even include the new Diana Gabaldon in my assessment. I think we can probably place a large amount of the blame on her for the Scots-Romance boom.
Taking all these factors into consideration, I have decided that my Ultimate Historical Romance Title, which I will apply to an as-yet unwritten masterpiece of fiction, will be (drum roll):
A quick check of the Library of Congress assures me that this title is STILL AVAILABLE. I can hardly believe it! I should probably get to writing TWSLM right away, but as I am on vacation, I think I will put it off until 2010.
ETA: My favorite title on this list was, hands-down, The Runaway McBride.