re: Backpack recommendations for month-long trip

North Thailand (Chang mai area)
Island hopping in south Thailand. Research the different islands a see what you like. Avoid Phuket unless you like the big all inclusive resort type thing.
Siem reap Cambodia
Hoi an and Hanoi Vietnam
If you think you can fit it in try and do bagan and inle lake Myanmar. Timewise it would be tough to fit Myanmar unless you're staying a short amount of time in each place.