if you are thinking about a trek in Nepal this year after the wet season, now is the time to check out the flights and prices. Thai and Singapore fly to Kathmandu via their home hubs, but I have found Singapore to be consistently cheaper by about $800 for the last 3 years. Consider if you want a stop over in either Singapore with Sing or Bangkok with thai as this may influence your decision. I have had great service on both but Sing is by far the cheaper. Start keeping an eye on prices as the bargains get snapped up quickly. Last year I paid $1400- return via Singapore.