I wrote about something similar in this post: https://jonworth.eu/bundling-trip-planning-and-ticketing-together-its-not-in-the-passengers-interest/
But I chose Haguenau - Arcachon as my route, but it's not perfect for a few reasons…
CRITERION 1
A trip that would in some cases need 2 changes, and in some cases 3 or more (the latter options would not be shown by SNCF Connect due to too many changes)
CRITERION 2
A mix of fix fare local trains, and yield managed long distance ones
CRITERION 3
A transfer across Paris, with time correctly calculated for a transfer between terminals
Haguenau - Arcachon complies with all of those…
... BUT I think there ought to be some more criteria
CRITERION 4
A trip of a length plenty of people would take
CRITERION 5
Part of the route with some operator *other than* SNCF
CRITERION 6
Some part of the trip where a short non-rail leg would help as a passenger, but all rail options are possible too
