"the majority of the opinions in the forum about Hoi An as a lovely and very beautiful little town !" Hoi An is undoubtedly quaint, pretty and very interesting. It is also overrun with busloads of mostly Chinese and Korean tourists from the mega resort hotels which line the coast, almost continuously for 20 Kms or so towards Da Nang.

It gets very, very crowded in the mornings and evenings when the hordes descend on the town but does get a lot quieter around midday towards late afternoon. It will be a lot warmer than Hanoi.

Each to their own, but given a choice of Hoi An or Hanoi, I would choose Hanoi every time , regardless of the weather.

As far as Hoi An, to me it feels distinctly delimited between the historic section and the newer town surrounding it. The historic buildings are mostly what people come for, with perhaps the addition of a nearby beach and the small ruins site at My Son (probably a half day outing or less to go out).

My own feelings is that I love Hanoi, could probably visit a dozen more times. And I'd happily go back to see more of Angkor and even revisit Luang Phrabang. But I saw Hoi An once and that was enough for me (other than to visit friends we made outside of town). Beautiful buildings in a decent sized historic district. But it's not just heavily touristed as described. IMO it's tourist oriented in an all-encompassing way I don't think is as true of the other places on your list. It's authentic... yet to me, from the restoration to the lantern dropping activity (a local festival it is not) being made a concession for tourists, Hoi An felt more like a theme park than any place else I've ever been.

Best 3 cities in Southeast Asia
 

Bangkok is top 3.

In Hoi An.....get on a push bike, and see some of the outlying areas during the day. Then wait for the mobs of day tripping tour groups to disappear, and enjoy dusk and the evenings.

We had a week there, staying v.close to the Old Town. Got hacked off the first day with the tour groups, and did our on thing on bikes after that. Back for a swim in the afternoons, then hit the town after dark.

It is so hard to say without knowing your interests. We are just finishing 2 months in Thialand,Vietnam and Cambodia and my favorite spot is one most never mention because it is not a touristy spot yet.
Quy Nhon is between Danang and Nha Trang, Vietnam with approx. 280,000 people. Very little English and we speak no vietnamese yet we really mixed with the locals. They are especially friendly and want thier children to talk to you to learn English.
Dont miss The Sportsman Bar. The bar is upstairs and restaurant on street level and quiet. An Australisn guy named Reece runs it and they serve good Western food.
warrsher

I agree with this. I bet you'll enjoy your trip if you would stick to one country at a time, and travel to the best cities in that specific country first before hopping on another one.

I think this is the best option for any one who can spend long time .
As I am limited by my vacation period ( 18 days ) , I prefer visiting the best of the Indochina county
The time it takes me from Luang Prabang to Hanoi is less than to Ventiane for example.
Discovering the Vietnamese capital, Halong bay , Ninh binh ,Cap Ha Sunday Market and the beautiful city of Hoi an will make me more enjoyable to visit places of beauty and fun I think.
And it will be very pleased to finish in Angkor temples.!