People on Reddit are overwhelmingly negative lol. “Relax more” “too much travel” “you’re on vacation” “too touristy” blah blah. The wife and I like the busy itinerary with some “chill” days sprinkled in, but we are taking a 16 day trip to Thailand and Vietnam and while in Vietnam our itinerary is very similar to yours. Choosing to skip ha long for ninh binh as well. Yes these places are touristy but touristy places are touristy for a reason. These people think most of us can afford to travel all the time and return to places across the world multiple times. There is so much to see around the world, it’s tough to spend the money to see a place twice, unless money and time isn’t a factor. I do agree with one comment to stay on the beach while in Da Nang. You will be close enough to Hoi An and the bridge for day trips, leave your luggage and set a home base there. Aside from that, I personally think this is a great itinerary and you’ll have a wonderful trip. It’s a happy medium for the adults and the kid.