I think the intra-Asia reward tickets for 20,000 and 30,000 miles are the best deals out there. I gladly use 30,000 miles for a WBC ticket on KLM TPE-BKK-TPE several times a year. Why not treat yourself and spend an extra 10,000 miles and enjoy an international business class experience? It's certainly much nicer than a first class experience domestically in the US.
NRT-BKK or NRT-SIN flights are over seven hours long. Just think of how many miles you'd have to spend for a shorter flight from the US to Europe.