Southeast Asia forum

Hi everyone,
My husband and I will be traveling to Indochina for 10 weeks from January till March. Arriving in BKK and leaving from BKK
We still don't know where to start the journey.
Shall we start from BBK, then Chiang Mai , Laos, Vietnam from North to South, Cambodia and then back to BKK from Siem Reap OR the other way around.
i.e. from BKK to Siem Reap, South Vietnam to North Vietnam, then fly from Hanoi to Vientiane and then Chiang Mai to BKK.
Is there any advantage doing this itinerary "clockwise" or the opposite way.
First, I thought about starting from the south so we would avoid the chilly evening in North Vietnam and Chiang Mai at the beginning of January and do the end of the trip shopping in Chiang Mai. But then, I'm thinking that the slow boat trip from Thailand to Luang Prabang might be better doing it this way instead of upriver.
Any suggestions?
Thanks in advance for all your help