1

Vientiane to Hanoi is a long long bus journey. The route and border is obvious. I would suggest you keep going south to Pakse, then tour Bolevan, and either cross from Attapue to Vietnam, or go from Pakse to 4000 Islands and onward to Cambodia and Siem Reap/Angkor Wat Cambodia, then to PP and down to HCMC via boat. The head north to Hanoi.

If not, what route were you considering from Veintiane?

2

As you are doing backpacking, I suggest you take a bus from Thailand to Laos, from Laos you cross the border to Vietnam in Nghe An provinces.
In Vietnam it is very easy to travel by bus, car, train to any place.
If you head south Vietnam you will have a good bus to connect to Cambodia from Ho Chi Minh city.

By taking this route, you will save your money and enjoy a trip through 3 countries properly.

Wish you good luck!

3

Get your Vietnam visa in Vientiene
From Luang Probang go to Nong khiaw by van, or boat.
to Muang Ngoi to Muang Khua by boat, from there i have not been. Research and i think you can cross into Vietnam at or neer Den Ben Phu.

Best i can do 4 beers. Cheers

4

From Luang Prabang you can take a 5 hour bus trip to Oudom Xay where there is a daily bus to Dien Bien Phu in Vietnam which is nice cause you don't have to changes buses at the border. I think it leaves around 08:00 or 09:00 in the morning. You could also backtrack a bit from Luang Prabang and go to the Plain of Jars and Phonsavanh which is a nicer place to visit than Oudom Xay. There are buses from there to the Vietnam border and to Vinh I think. Maybe check http://hobomaps.com/TravelPDJ.html for bus schedule details.

5

or you could reverse the laos section and go into laos from nth thailand, towards luang probang, onto vv then vientienne, then to savannakhet where you can get a bus to hue, vietnam which doesn't take too long and roads are decent. in vietnam you can get sleeper trains which are comfy and cheap enough so from hue you could go to hanoi by sleeper train then head down vietnam from hanoi to hcmc. Yep, its backtraacking but its about the same travwl time as going from lp to hanoi on a 24hr hell bus ride.

6

So our plan was to travel up from Luang Prabang to Nong Khiaw then via Muang Ngui Neua to Dien Bien Phu and across to Son La then Hanoi. Does anybody have any idea of how long we should allow for this trip/whether there are nice things to see/do along the way?
Thanks everyone for your help so far!

7

I'd allow a week so you can stop and spend 3-4 days visiting where you're traveling. The trip could be done in two days (the Vietnam side is pretty speedy!), but you'll be looking out the wiondow at some cool places going by...

One can also go from Nong Khiaw to Xam Neua/Vieng Xia, then cross at Nameo. There is a daily bus from Xam Neua to Thanh Hoa (with connections to Hanoi). Xam Neua to Hanoi by bus is one long-ass day (14+ hours), but the scenery is unique and wonderful. Houaphon Province in Laos is a gem of a destination. We just spent another couple weeks there - hardly a tourist, yet it's not all that "out back."

Oh, and you can take it in as slowly as your visa allows!