I've wanted to check out Bobet's museum for a couple of PBPs now but have never done it. Hopefully I'll be there when it is open and finally get to pay my respects. I may even make a point of visiting the Terront plaque in Versailles on registration day.
Going by my timings and presuming the town is still enroute, the museum must only be about 2 or 3 minutes off route and very simple to get to looking at my track from 2015. Plus, you can ride up to the entrance on your bike and no long walk to get to it. So a 5 minute stop at the museum would only loose you about 11 minutes time at the most. Maybe worth leaving some room in your bag for a souvenier.
I have always looked for places of interest on Audax's, mainly battlefields, especially in areas that I have never been before. One example is one of my favourite films from years gone by when I was little, "Whistle Down the Wind" with Hayley Mills. About 3 years ago, I watched the film, again, and thought the village, Downham, was familiar to me. That weekend, I was riding, "Season of the Mists" once again, and suddenly realized that is where I know it from, the ride passes through it. Hence on the day, it gave me something to look forward to and visited some of the film locations in the village and took my pictures.
If PBP was to pass further North, I doubt I would ever get to Brest as there would be to many battlefields to visit that I have never been to, like the " US Breakout at St Lo" and the "Falaise Pocket".