I have traveled throughout Thailand on planes, trains and automobiles. The new trains just rolled out look amazing. I can't wait to try these. One of the best trips I ever took was from Chiang Mai to Malaysia. It was great and now the service looks like it is truly going to improve.
http://www.bangkokpost.com/news/general/1119720/reservations-now-open-for-travel-on-flash-new-trains