Rate my vietnam itinerary

This august im going to Vietnam and I’ll have about a week to explore the central and southern parts. I was thinking of spending 2 nights in Hue, 1 night in Hoi An, 2 nights in Da Nang, and 4 nights in Ho Chi Minh. However, I have a few doubts.

First, I dont know if 2 days in Hue are enough to see the main things. Second, I’m not sure whether just one night in Hoi An is worth it, considering everyone says it becomes much more beautiful in the evening.

I’m also unsure about Da Nang. I’ll obviously pass through it on the way to Hoi An, but I’ve heard it’s mainly a coastal city, so i dont know if its worth visiting, or is it mostly just for relaxing at the beach?

Lastly, I’m wondering whether 4 days in Ho Chi Minh City are enough.

I’ll already be visiting Hanoi and the northern part of Vietnam in the previous weeks, as I’ll be busy with some volunteer activities there.

Thanks a lot for any advice!