I was looking on United's site, but couldnt find any info. I know I can use my United miles on a full ticket on any of the Star Alliance partners (including Thai), but what about upgrades? is that possible? If so, what base fare would I have to buy to upgrade to business class? I heard that you can "request" the upgrade, but cannot confirm it at the time of purchase. How does that work??
Also, I saw on the Thai site that you can upgrade service on the day of travel for a fee. Any info on this??