I have 9 days to spend and would like to go to Vietnam. So far I have sketched out the following itinerary:

Day 1 - Hanoi
Day 2 - Hanoi
Day 3 - Halong Bay
Day 4 - Hoi An
Day 5 - Hoi An
Day 6 - Hue
Day 7 - Hue
Day 8 - HCMC
Day 9 - HCMC

I'm more into sightseeing and experiencing the food/culture, less so seeing temples and palaces. Is this doable, or should I change it? I also noticed that there are some organized tours that go to the same cities, should I consider it to maximize my time? I will be travelling solo.