How far apart these languages are, in data.
I love this. What about Sardinian (Sardo) and Corsican (Corse)?
I spent a month in Corsica last year (see below) and I LOVED the exposure to the Corsican language, especially since it's close enough to Italian that I could converse quite well. I actually went to a Corsican bookstore in Bastia looking for a history of Corsica written in Corse, but, alas, the only history of the island that I could find was written in French.