You can burn 60000 United miles on a Star Alliance pacific award, fly EWR-SIN-DPS, the award allows one stopover in SIN, then buy a tix from SIN-BKK. If SIN-BKK is too expensive there might be cheap fares from Johor Bahru (forgive me if I butchered the name), a city in Malaysia right next to SIN.

60000 miles gets you Executive Economy- go to the SQ board and search for a trip report (or search under my username for my report)- although it isn't business class overall, the service is just as good, seats are very tolerable for a 18 hour flight. This way you have no overnights, one stopover, and only have to burn 60K miles! Availability from EWR is quite good.

As the other posters suggest, JFK-BKK on TG is also a good option. Read the TG board for reports in their enhanced economy class, it's supposed to be similar to SQ's.