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Depending on your connection time at LAX you could check your luggage (if you check at all) only to LAX and try w/UA to allow you on their NRT flight. While this is technically not possible, they might still allow it, since you're holding a UA ticket and change to a UA flight.
Good luck![/B]</font>
This is a good suggestion cesco g. I've done it and since you are using UA miles, they might accomodate you if there is space available all the way to BKK not just to NRT.
Also, since TG business class is dreadful, (new and old) you can try to upgrade at the airport to F by paying $600 o/w. They have even allowed this on free tickets for me since they can generate considerable cash this way. I don't know if Varig does this but Thai does on all their routes for different prices. Ask TG for the airport standby upgrade and say you want to go all the way to BKK. For some reason it costs $800 between US and Japan but only $600 between US and Thailand despite the fact that you fly through Japan. For the 17 hour journey, I find this worth it.
CDG 1K