Vietnam is a country of breathtaking natural beauty with an incredible heritage that quickly becomes addictive.You initially planned 30 days for Vietnam, but happy to get a longer Visa and stay more like 40 days there (arriving first week in December or January because this time is happiness with people Viet Nam). As usually it is a big task to create an itinerary, and it was slightly more complicated as You will spend Christmas and New Year there (first time not being in Europe for both). It seems spending Christmas in Hoi An and New Year in HoChiMinh  is best your preferred option (not able to make it to HoChiMinh for Christmas). If you are lucky you can join Lunar New Year in family’s VietNam. Please listen to me, it's worth a try.

Considering these constraints you try to combine some cultural bits, some outdoor activities and of course visiting the sights that are famous.  If you are solo traveller, and with a daily budget of around $50 You should easily travel around (with some funding for some parts that could be more expensive, like trekking or Ha Long Bay tour or a flight if required), beside You can buy a motorbike Viet Nam form backpacker at here or other site if you knows.

Checked other itineraries posted here already (which gave me further ideas), and all the reading and researching led me to this first initial plan, and would welcome any comments and advise.

 

Day 1: Heading to Sapa, Best place to climber

 

Day 2 – 7: Sapa (trekking, maybe add a day trip to one of the local markets I read about) – taking the train (either daytime or overnight one) to Hanoi.

 

Day 8-10: Review Hanoi capital VietNam

 

Day 11 – 13 : Ha Long Bay (really want to experience this area). Take the train in the evening of day 13 from Hanoi to Nimh Binh

 

Day 14 – 16:  Ninh Binh – sounds an interesting area and read good comments here. Taking overnight train to Hue.

 

Day 17 – 19: Review Hue. You can like foods and life here. It’s very cheap.

 

Day 20 – 22: Hoi An (spending Christmas Eve and Christmas Day here)

 

Day 23 – 26: Kon Tum – adding a place off the beaten track, and the description of the area sounds good to relax a bit, and visiting a minority village in that area

 

Day 27 – 30: Flying to HoChiMinh City (it seems I need to take one flight as Kon Tum is a bit away) – staying New Year’s Eve in HoChiMinh City

 

Day 31 – 37: Mekong Delta + Phu Quol Island: Exploring the Mekong Delta and enjoying a few days on the beach (will finish my trip before heading home on a Thai island beginning of February(spending Lunar New Year here).

 

Day 38: Ha Tien and crossing into Cambodia (can you get a VoA at that border? I have read conflicting information about that)

 

Aware that I only spend 3 days in most places. While you prefer staying longer to explore and experience places a bit more, it seems you see a bit more of the country this way. I will try to travel manly by motorbikes (adventure) or train (more comfortable). But it would be appreciated to get any feedback or comments regarding this itinerary, as you want to ensure that I will have a great time in Vietnam.