UA.bom really wants me to go through Bangkok and connect to a Thai airways flight in the morning. That has me getting into BKK at midnight when it is really too late to do anything, and I've been there, done that a dozen times or more.

LAX-SGN looks more interesting and would get me a new stamp in the passport. But if there is a visa requirement for an overnight transit that could be a deal breaker.

Any advice on doing this as an overnight transit? Recommendations to make it easier?

Any thoughts on Vietnam Airlines for that quick hop to PNH? How bad could it be?