I did it in Bangkok US embassy. Got my jumbo passport (I believe 14 more pages) in 6-7 weeks. I was staying in Pattaya so I decided to mail my passport through DHL to the embassy. There are few steps you have to do and I recommend you watch the video(s) on renewing passport outside of the US. The renewal fee payment link was super difficult to find and I eventually went to US embassy in Singapore for the link.