Current touristy plan: find "Shakespeare and Co." bookstore.
Edit: did indeed find it, and it was pretty adorable. They had a publicly-usable piano upstairs (!) so I played a bit and talked music with other piano nerds that happened by. Skimmed Pullman's "The Good Man Jesus and the Scoundrel Christ". This seems like a pretty good review of it, but I take issue with two things. One, I had a definite feeling that "the stranger" is St. Paul, as organizer and "historian", but also that he played the role of St. John, the mystic, he of Ἐν ἀρχῇ ἦν ὁ λόγος, inserting truth into history. The other is that Pullman has to name the other brother "Christ", to avoid spoilering the fact that he is Judas. Anyway seemed like an okay book, but didn't stand on its own two feet the way His Dark Materials did.