Atlas or UAL to HKG then commercial ticket on Thai or anyone else to BKK. Avoid DMK unless it's really worth it financially or based on location. Beijing is also an option, as is NRT but those are usually more money to transfer thru. Avoid Shanghai. Never tried Taipei, never needed to. HKG is BY FAR the most convenient, I've made 45 minute connections there before. Keep your uniform on until you have an onward boarding pass or they'll herd you like cattle to the wrong part of the airport, you may need to ask a favor of a security guard to let you into the transfer counters but if you have your uniform and ID this is not an issue.
You CAN non-rev to China on a passenger airline without a visa as long as you have a ticket out of China. You CANNOT non-rev to China as a non-rev on a cargo airline unless you have a Chinese CREW visa (transit or tourist visas will not be accepted). PEK has many transit counters you just need to know how to use them (as in sometimes you have to walk a big 180 around to the other side of the arrivals hall) and they're limited in their operating times. I've done this numerous times as I live in Pattaya.