I'm hoping to travel and return from Paris to Vernon-Giverny on July 14 (Bastille Day). I will have a Eurail Global Pass and am unsure if I will need to reserve a seat. The two trains I have identified are Intercites and most advice I have read is that it is not possible to reserve seats on these trains. However when I look at booking options it suggest reservations are a good idea. I'm not sure if I should reserve or not.
I have read is that it is not possible to reserve seats on these trains.
That is correct.
However when I look at booking options it suggest reservations are a good idea.
Exactly where are you looking?
I don´t know what you paid for a Eurail Global Pass but you can get return first class Paris - Vernon tickets for under 25€, main compartment tickets at 18€.
I was looking at https://ricksteves.raileurope.com/us/rail/point_to_point/triprequest.htm and it suggested a reservation was recommended.