Route notes
Why this routing works
This route is built as a simple round trip from Saint Louis with one open-jaw in Southeast Asia: fly into Phnom Penh, continue overland, then resume the ticket from Hanoi for the flight home. That structure keeps the long-haul flying on a single framework while leaving the Cambodia-to-Vietnam segment flexible on the ground.
With three weeks total, the sequencing is straightforward and avoids backtracking within the flight plan. Arriving in Phnom Penh and departing the region from Hanoi spreads the trip across two cities without requiring a return to the original arrival point, which is often a practical fit for a shorter multi-stop trip.
In economy, this routing sits in a published sample price range of USD 1,731 to USD 2,640 for travel in the October to December season, with departure shown in November. The key ticketing feature here is the gap between Phnom Penh and Hanoi: that segment is not flown on the ticket, so timing on the ground needs to line up with the onward international departure from Hanoi.