Originally Posted by invisible

May I suggest not to spread all over Vietnam? Please take into consideration that if you count time to get from place to place, it will easily add on 3 days and more.

I am not a big fan of Saigon (mildly speaking). I would suggest to replace Saigon with Dalat and limit your travels to 3 places maximum. For Hoi An you would need 3 days only if you plan to order some clothing made from one of local shops. If not, 2 days/nights should be sufficient - one for Marble Mountains, My Son and coming back via boat, second day for the town itself.