Hi Judy -
We spent almost 3 weeks in Hong Kong, Bangkok, Chiang Mai, and Siem Reap. We didn't make it to Vietnam on account of my husband twisting his ankle pretty badly, so one day after we arrived in Saigon, we left for home.
Your itinerary sounds wonderful and 4 nights in Bangkok is fine as well as the 3 nights in Chiang Mai. We stayed 6 nights and that was too, too long. Now I can only give you my personal opinion and others may disagree.
Can you please let me know which conducted tour you're taking for Laos, Cambodia and Vietnam? We do hope to get back to see all that we missed. Siem Reap is well worth re-visiting. I was totally impressed with Angkor Wat andAngkor Tom.
Hope this helps, Judy.
Cheers to all, Rose - Los Angeles