Coming in January

If you want to 'sample' the culture, Nha Trang is about the last place as it is so 'multicultural.

VietNam is a 'binary' country -  people either love it or they hate it.

With all that time in the country it would be a waste not to do an extended trip by entering through Ha Noi (airport), going to Ha Long Bay (bus) and Sa Pa (rail). (Both destinations arranged through Ha Noi).

Do not return to Ha Noi direct but rather take the bus over the mountains to Lai Chau. Very few people get up this way and the vistas are equivalent to the Alps.

After Lai Chau is a bus trip to Dien Bien Phu where the French showed the futility of defending a valley, The another bus trip to Son La, where there is a (former) French jail and other historic monuments. You then return to Ha Noi.

(Note: Ha Long Bay travel is part of the tour; rail to Sa Pa should be purchased at the rail station (only - no way at 'travel agents' or hotels)(before your trip to Ha Long Bay).

The journey from Sa Pa through Son La is by local bus (try to get a seat near the front so the smell of cigarettes and unwashed bodies is behind you.

You can leave unneeded baggage at a Ha Noi hotel (as long as you use it when you return from the side trip) - just make sure it is well secured. Doesn't harm to put a large label on it with your name and return date (and VND100,000 tip to desk clerk to give it special care, when you pick it up).

Rail tickets have to be purchased by each segment.

Then to Hue (rail), the former Imperial Capital, Da Nang (bus)(any bus carrier) through Hoi An for it's beaches. (Side trips include the Marble Mountains and Cham monuments - the latter south of Hoi An)

Rail to Nha Trang; bus (ONLY Mai Linh Express or Hoang Long carriers) to Da Lat, then bus to Mui Ne (sand dunes) bus or rail to TP HCM.

A good alternative is Da Lat and bus (Mai Linh Express) to Buon Ma Thuot (my home town here) and sample the fresh air, fresh coffee and tea. The pepper is good, too, you might not want any rubber, though. Historically it has another former French jail (in working condition); great food (try the venison). Then a Mai Linh Express to either TP HCM or back to Da Lat to get a bus to Mui Ne.

After sampling TP HCM 'culture' you should explore the MeKong buying inter-city bus tickets (Can Tho has the floating market and the impressive bridge).

No need for tours, just D-I-Y.

When you reach Rach Gia, head west to Ha Tien (great cheap, fresh sea food in the market at night) and then the modern ferry to Phu Quoc Island. Afterwards, fly back to HCM.

Over the years I have travelled all over VietNam and the variety is staggering.

Transportation
The reason I recommend Mai Linh Express or Hoang Long is because their drivers are actually trained whereas the OpenTour buses are driven by drivers who might even have real licences, drive every day of the week and have little respect for safety. At least when they kill themselves there i one less idiot bus driver.

Rail is as fast/slow as bus. You should take it between Ha Noi and Hue as well as Da Nang (after you finish in Hoi An) to Nha Trang. Both these journeys are around 12 hours.

Accommodation
There is no need to book hotels anywhere. Reckon on USD$20 in larger cities and USD$12-15 elsewhere except Sa Pa and Phu Quoc Island. Hotel rates are always higher in Sa Pa on Friday and Saturday nights.

Tet surcharges
Always people to exploit travellers, you will find travel around Tet not only expensive but nigh on impossible to get. I suggest you plan to be in a larger centre for around the 4 days (day before and three after).

MeKong Travel
Use Mai Linh Express "local" service between the towns.

Food
About USD$6-10 for basic meals (banh me bread roll sandwiches and noodle soup (pho) meals).

Plenty of opportunity to splurge when it strikes you. Choose the local specialities.

In Ha Tien the best food is in the market - table are set up at night and you choose your meal from different vendors. VND30,000 is filling, VND100,000 hard to leave the table. Beer extra. The city also charges very small amount for Foreigner size tables!

If eating 'local' choose the busy places, the food is fresh and the crowds the recommendation.

Visas
You can get a 3-month tourist to enter, then extend after you are here.

This web site is less for tourism, there are many others that have lots of traveller info. Always treat TripAdvisor with a large pinch of salt and NEVER buy anything through them (owned by Expedia).

Communications
VietNam is GSM country - register with Mobiphone for full coverage and cheapest service. InterNet cafes all over and free WiFi everywhere.

Money/ATMs
The USD$ is the main international currency here (nice clean $100 bills get you the best exchange rates except at banks). In smaller centres jewellery stores give the best rates (ditto in HCM behind the Ben Thanh market).

ATMs everywhere, like mushrooms. BE CAREFUL, some are 'network' where double service charge apply. Ask your bank the best ones to use.

Better to use ATMs where there are security guards. not only safer for you but also the ATMs are less likely to have been diddled with.

Enjoy your trip.

I'll send a different point of view for balance. While it is true that Nha Trang may not represent the diversity of Vietnam, it sounds like you are more interested in a place for extended stay or semi-retirement. In that case Nha Trang is a wonderful destination. I spend my winters in Viet Nam. After 4 winters in Ha Noi and Ho Chi Minh, I discovered Nha Trang -- and I'm never going back to the big cities. Indeed Nha Trag is everything that HCM and HN are not: it is quieter, cheaper, cooler (I guess that comparison is for HCM), better smelling, less congested and definitely friendlier ... and of course we have a beach (many kilometers of it). So the real question is: Are you on a touring vacation or wanting an extended stay. Nha Trang wins for the latter.

Housing is reasonably plentiful -- in most any budget range. And as usual you get what you pay for. My friends are appalled at my $800 rent -- but  it is a brand new, 2 br top floor fully serviced apartment with sea view, great security, etc. But I know people living in $250/mo rooms... so take your pick. You can find apartment listing and services by googling something like: "Apartments in Nha Trang" [or PM me and I will tell you specifics about some I know]