Route notes
Why this routing works
This is a compact North America multi-stop routing from Lyon that strings together two short East Coast stays, an overland move into New York City, and then a westbound progression across the US before returning to France. The order keeps the transatlantic crossing at the front, uses the Washington DC to Montreal sector as a short onward hop, and leaves the domestic US flying for the second half of the trip.
The open-jaw between Montreal and New York City is the key structural feature here. Because New York City is reached overland, the ticket separates those two points rather than forcing a return flight or backtrack. That can be useful on a short itinerary where one surface segment fits better than another flight and still keeps the overall route moving in one direction.
With only about a week total and economy cabin throughout, timing matters. The one-night stops in Washington DC, Montreal, and San Diego suggest this itinerary works best when the connections are intentional and the longer stay is concentrated in New York City, with a shorter stop in San Francisco before the final return to Lyon.
From a ticketing standpoint, this is a straightforward multi-stop itinerary rather than a round-the-world pattern. It combines transatlantic flights, short-haul North American sectors, and one overland gap into a single routing framework, with June departure timing falling in the apr-jun season window provided.