I have the Arrival, and it's always a guess on what exactly will be considered a "travel" expense for bonus points. And I imagine that's always the case with cards that have bonus categories (which depend on how the purchase is coded).
I've had hostel-booking sites NOT count as travel purchases, for example, and had some theme/water parks/roadside attractions count as travel, but not others.
Anyway, I recently started using one of those smart-car rental services (Car2Go). And it turns out, they count as a travel purchase for double points. Woohoo! Wasn't expecting that.
Have you ever had a purchase unexpectedly get you bonus points? Or bought something you were SURE would count for a bonus category, but didn't?