Planning a Vietnam Trip- Looking for Feeback on our Itinerary

Hello
Kindly need your feedback. We are planning a Vietnam trip in mid July to late July and thinking of entering from North then Central and exit from South.
North -we are planning Hanoi, Ha long Bay
Central- Da Nang, Hoi an
South- Hoi chi minh city.
Does this sound like a good itinerary for 8-9 days. Please recommended a must visit places we should add.

Thank you