I travelled up north from Luang Prabang to Luang Nam Tha and then another 3 hours up the mountains via truck to Muang Sing. With each mile travelled, I felt like I was really, truly getting off the beaten path... although was still glad for a few guest houses with open doors and places to eat when we arrived ;-)
I went to the local/community run trekking office in Muang Sing the following day and found a guide to take us even further up the mountain for a homestay trek over 2 days. This was one of the best things I've ever done in my life - such an eye opener about a life without electricity, cars, roads or running water. Nonetheless, I also discovered a lot about the commonality of humans, family life and laughter.
I've done homestays in Sapa, Vietnam and loved the interaction with families and the slow time it takes to wander through the countryside... but doing this in northern Laos took it to a whole new level. Highly recommended. about 8 years ago
Take a bus. It's not how, it's where you go. If you head up to the Phongsali area, you will be very much off the beaten path. One disadvantage is that there is really not much to see, unless you like looking at a lot of trees and perhaps a village here and there. Also, lots of cool islands in the south that the tourists don't get to. You have to charter your own boat to cross over form the main islands in Si Phan Don. Good for walking around and some pretty scenery but unless you know soemone in one of the villages there people will wonder what the heck you are doing there. I visit my friends' families while in laos and there is really not much to do but sit around and sleep in the daytime (too damn hot to do anything else), some of the men drink themselves silly, and then you eat, and drink laolao at night. Others get up at the crack of dawn to fish or work in the fields... about 8 years ago