I am halfway into a book written by a British woman (Zoe Cano) who rides a Bonneville in the UK, and around Europe.
She arranged to purchase a Bonnie in the US to ride coast to coast. It's a nice read. she had lived the in US in the past, so it's not a culture shock theme. Just about her biking adventures and the nice people she meets along the way.
She made a point to not run the Route 66 way, as she thought it might be better to take a Southern route.