HI! From Nha Trang to Mui Ne beach if you have time to do The Central highland from Nha Trang - Lak lake - DaLat - Mui ne - Mekong delta for 6 days. all of the place you been are touristy so why don't you try get of the beaten track and see the real Vietnam ...-snip-
[ Edit: Sorry, no promos please. ]
Itinerary looks great and the comments are also excellent.
I suggest you hire a motor bike at Ninh Bin and spend a day or 2 - magnificent scenery (like Halong Bay on land).
While in Sapa get a tour to the Bac Ha on market day.
I was a tour guide 30 years ago in Europe, SE Asia & north Africa and until Vietnam had never been on a guided tour other than my own. In Vietnam the tours to Sapa (+ Bac Ha) and the Mekong Delta were cheaper than I could do myself so I took one of each - fantastic value.
Also blew the budget on the back of an Easy Rider motorbike bwetween Saigon & Dalat which turned out to be well worth it.
Having said all that, Vietnam is my least favourite country in SE Asia after Singapore as the people are much tougher than surrounding countries.
I recommend Hue too, but give Dalat a skip - what a disappointment for me! If you spend extra time in Sapa then you'll not miss the mountains in Dalat.
Hoi An is defintely a must stop over. Here at the moment and its a great place. Danang is not a bad city but its not for tourists its for business.
Vietnam is very easy to travel through - tourist bus network well established - really not stressful.
The people are harsh, but just the ones exposed to too many tourists. Give them a chance and strike conversations with locals next to you on a public bus or sitting on a stool at a street cafe and you'll see they are friendly too.
I think that the itinerary that you have put together is really great and covers the main places of interest in Vietnam.
One thing I would say though is that I definitely think you should cut out Vinh. I arrived there after crossing from Laos to then get a train up to Hanoi, and let’s just say it wasn’t a great welcome to Vietnam. This was a couple of years ago though and things might have improved since then. Also, while I was here, I found that there wasn’t anything of real importance to do during a visit to this town apart from using it as a base to travel into or out of Laos or to travel from either north to south or vice versa.
I think that you should use this time instead to travel from Hanoi down to Da Trang and then onto Hoi An.
Please be aware that during my travels within Vietnam, I found that the train stations do close around lunchtime for a couple of hours at a time. I am not sure if this is still the case though so you might have to look into this. So if you are intending to travel by train either make sure that you go to the train station early in the morning or late afternoon/ early evening so that you don’t arrive and the office is shut.
One tip that worked well for me was once I arrived at each destination/ station; I went straight to the ticket counter after getting off the train and booked my on-going train journey. This is great if you are on a tight schedule or only want to spend a couple of nights at one place. This is because train tickets can get booked up very quickly during some times of the year especially during the holiday seasons and it will mean that you are not left staying in one place which you really don’t enjoy rather than being able to travel onwards with your trip.