Phonsavan (Plain of Jars) is well worth the time and effort. Also very few Westerners. It's only a 40 minute flight (Lao Skyway)from Vientiane to Xiengkhouang and a short taxi ride from the airport to the city. There's also a flight from Phonsavan to LP. Renting a bike in Vientiane and Luang Prabang is a good way to get around and explore areas outside of the cities.

Your itinerary only seems to include major cities apart from Phi phi, which is a major tourist destination. Given the number of cities and countries you plan to visit in 5 weeks, cities are all you will see.
Firstly you need to factor in travel times between destinations. Then think about what you really want to see and do in each place, and allow for that. Also allow for delays of transport, or days of sickness. I think you will find you are trying to do too much in 5 weeks. If your tickets are booked into Singapore and out of Phuket, then a flight from KL to somewhere like Hanoi makes sense. Then work your way through Laos to Luang phabang, take the boat to the border, and visit Chiang Mai. Omit Vientiane if you want to see Chiang Mai or Chiang Rai.
To be honest I would leave out Vietnam, as you really don't have time to do it justice.
You don't mention when you are travelling, and this might affect the best routes and destinations.

I am riding into Vientiane today from Hanoi as part of a longer trip. From Hanoi I followed the Ho Chi Minh Highway down to QL7 and headed west to the NamCan border crossing. My route in Vietnam took me from Ha Tien in the south to Hanoi then back down the HCMH. The HCMH was by far my favorite road to bicycle in Vietnam. I also loved the mountain towns heading towards the Lao border.
This route took me through Phonsavan where I wanted to see the Plain of Jars. Route 7 continues to Phou Khoun where I turned south on Route 13 through Vamg Vieng to Vientiane.
Route 7 in Lao takes you through the mountians and past many small villages. Excellent views and great people - although a bit more reserved than those in Vietnam. Guesthouses are a bit scarce after you pass Phonsavan but I found one each night.
Route 13 starts with unbelievable views and then heads down out of the mountains. The road is busy but nothing like Vietnam. Drivers are more courteous and generally drive slower than in other SE Asia countries. The road is broken up in many places. Guesthouses are abundant along this road.
I took a bus from Phonsavan to Luang Prabang and back to get some work done on my rear wheel. The road from Phou Khoun to Luang Prabang was slow going by minivan. There were many landslides which turned the seven hour ride into fourteen hours. You didn't say what month you were planning to to this ride but right now it is rainy season.
I was very happy with the route I took from Hanoi to Vientiane but I'm not sure you could do it in eleven days.
You didn't say what you mean by 'safe'. I found riding on the road with other drivers to be safer than other countries in SE Asia. As far as safety - I never felt unsafe. As far as camping - you have to be aware of land mines.
-Scott
In SEA, I think there is not a lot of options, but there are a few ones.
Hanoi (Vietnam) is pleasant most part of the year ( a town up North has a cooler climate).
Bagan and Mandalay (Myanmar) also pretty good climate, can get a little hot during the day, but cool nights.
Chiang Rai also cool climate, but only part of the year (Thai winter about 3/4 months only).
Luang Prabang is cool climate most part of the year (as well other towns in North Laos).
Hi Lincoln.
I guess the typical one on that route these days is pretty much what you said,maybe the opposite direction.
Start Bangkok,up through Chiang Mai to Laos.Highlights of Laos (e.g. Luang Prabang etc)and down to 4000 islands.
A week in Cambodia for PP and Siem Reap.
Then over to Vietnam. ..HCM and travel north up to Hanoi,finish there....

I am planning my month long itinerary in Myanmar (during upcoming month of November) and need to decide how many days I'd allot to Bagan. Most of my decisions are based on my passion for photography.
https://www.flickr.com/photos/phil_marion/albums However I am considering allotting extra time to Bagan if the monasteries are accessible for visit as they are in Luang Prabang, Laos. In Luang Prabang I noticed the monasteries were not well visited by tourists during the midday heat or early evening and often I'd be one of a handful of tourists in the monastery at those hours. Consequently it was easy to obtain conversations with the occasional novice monk interested in practicing his English. As a result I was approached by a monk to help out with his evening English classes. I also rented a river longboat and treated 13 monk and novice monks to a trip to the Buddhist cave of Pak Ou on the Mekong River. Upon return to my native country I've sent English language reading material for use by novice monks who need access to English reading material.
In Bagan are most of the monasteries considered working monasteries? or are many abandoned? are the novice monks as outgoing, friendly and eager to meet tourists as they are in Luang Prabang? I would devote a considerable longer period of my visit if this were the case. Thanks.

Hi there!
My husband and I are planning on traveling to SE Asia in June. We were thinking of starting in Vietnam and traveling around for about 10 days before we head to meet friends in Chang Mai for a week at the end of the month. We are not big city people and are more nature people. We were thinking of starting in Hoi An for a few days and then go to an island and possibly visit interior Vietnam countryside. My questions are 1) what are good suggestions for an island to visit that is a shorter flight or boat from Da Nang/ Hoi An in June? I realize it is rainy season in a lot of areas. We are open to flying to another country for beaches since we are headed to Thailand after but have already done Ko Samui in Thailand so are wanting to go more off the beaten bath. 2) any beautiful cultural countryside experiences we should not miss in Vietnam?
Thank you so much for your advice! I really appreciate it.
There are no buses from Phonsavan to Udomxai or Luang Namtha, at least that I'm aware of. There was a minibus service from Phonsavan to Luang Prabang when I was there, taking roughly 8 hours. You might be able to make it to Udomxai in the same day if you use this service. There are no direct buses (at least not at a convenient time) from Udomxai to Huai Xai, but it's easy to make the trip in a day with a change of buses in Luang Namtha.
Of course, one has to ask the obvious question: why don't you just travel from Phonsavan to Luang Prabang, and then take the boat from there to Huai Xai, instead of in the reverse direction? You could then travel from Huai Xai back to Luang Prabang by bus, if necessary.
