I booked RT to SIN last night from CHS, I was pretty flexible, but got CHS-EWR-HKG-SIN and SIN-ORD-CHS all cleared R class at booking. Had tons of availability in mid June. R4, R9, R4 etc. I could have easily booked out of IAD as well. Not sure when you are trying to go.

quick search: flying to SIN on the 13th Jun, return on the 20th
http://www.flyertalk.com/forum/attac...33040&stc=1&d=
http://www.flyertalk.com/forum/attac...79641495457964