@codewiz Look into Siem Reap/Angkor Wat in Cambodia, Halong Bay, Hue, Hoi An and the Mekong Delta in Vietnam, Chiang Mai/Chiang Rai in Thailand, Vientiane and Luang Prabang in Laos.
@codewiz Good choice! I assume you meant HCMC to Hanoi... Hoi An is a great place to stop in between, too. Love the buildings in the old town. And yeah, there's plenty to do in HCMC already, if you're pressed for time you might as well stick around the city. The Delta is nice to see if you have a more leisurely schedule.