We want to do the same KentChoong, or somebody else.. How did you do it and is it possible in the rainy season? Thanks you!
I don't think the rainy season should be an issue. If you have time I would recommend to take the boat one hour up north to Muang Ngoi, and maybe stay a few nights there. It is a lovely village, with some great scenery you can see without the need of a guide.
From Muang Ngoi you can then take the boat to Muang Khua. I would advise to put your name down for that trip north (either at the boat landing in Nong Khiaw if you don't want to stop at Muang Ngoi, or at the landing in Muang Ngoi). Sometimes the boats do not leave for the journey if not enough people will join, or you have to pay more for the whole boat.
From Muang Khua you can take a bus to the Vietnamese border. I didn't do that specific trip (only got as far as Muang Ngoi), but some of the people I met went from Muang Ngoi to Vietnam using that itinerary.
I am also looking at some travel options in the North of Laos, probably in late May or early June 2014, only just beggining to pull a plan together now and so i'm very interested in this topic. Last August (2012), I travelled from DBP to Sapa via an overnight stop in a small town, Phong Tho. We hired a 4WD and driver. This is clearly more expensie than a local bus but our reflections on our month in Vietnam, include this trip over one and a half days as one of the highlights. The scenery was amazing. The obvious benefit of having our own vehicle was that we could stop and take photos when and where ever we wanted.
The boat north to Muang Khua doesn't leave every day but put your name down and others will follow at the boat landing. One or two agents in town might be able to organise a boat for you. There is a bus that goes to Oudomxay, from here there is a bus that travels daily to Dien Bien Phu via Muang Khua. I took the boat this May, it takes six hours with a few stops on the way to deliver mail and pick up people, half way we had a tremendous thunderstorm and had to stop, we couldn't see where we were going. The journey is amazing, well worth the 150,000kip we each paid, there were four of us.
At Muang Khua, walk up from the landing and follow the road, at the top of the hill opposite the biggest hotel in town there is a tourist office, it was unlocked and empty when we looked in but there are posters on the wall and information outside about the bus to DBP. The travel guide I had said you had to cross the river to get the bus at 6.30am, not any more, it arrives about 11am on the main square, it will be fairly full, fold down seats in the aisle, luggage on the roof.
Myself and three others travellers plus a few Vietnamese were on the square by 6am in the hope of the early bus despite the notice at the tourist office so we waited in the cafe on the square, around 10am a man turned up on a motorcycle asking who wanted to go to DBP and selling tickets for the bus, 50,000kip. There is a notice in the cafe about a man who can drive you but he is expensive.
The journey is amazing, there are new bridges over the river which is why the bus now stops in town, it takes five hours of which one is spent passing through border controls, travel at the weekend(I did Saturday) the Laos side will charge 10,000kip for overtime. At the Vietnamese border the man who screened us for bird flu also changes money.
At DBP bus station you will be besieged by ticket sellers for onward journeys, you'll have missed the last bus to Sapa but buy a ticket for the next day and there are plenty of rooms available nearby. For Hanoi, there are overnight buses but I recommend you spend a couple of days at least in DBP, it's not an obvious tourist town but the battlefield can be explored, old tanks and artillery are dotted all over, the victory monument has great views and the people are really friendly.