For the vast majority of people on this forum flying is the only option to SEA.

also many of those visiting will want to visit the more touristy places and would be uncomfortable in the non tourist places

fine advice in principle but not so practical

If you're from Australia, Europe or North America, yes you fly to SE Asia but once you've landed at your gateway city, you can travel by land from there. Singapore is an important gateway city for flights from Australia, Europe and North America, while Bangkok serves the same purpose for flights arriving from Australia/NZ and Europe but not North America (since 2015 no airline operates a direct route between Bangkok and North America).

Why would anyone be "uncomfortable" traveling in the non-touristy places? If you don't want to visit non-touristy places, why even come?

I recently met a young American family. First time in Asia. They fly from Kuala Lumpur to Chiang Mai. After a couple of days there to get acclimatized, they catch a bus down to Lampang. Lampang receives the odd foreign traveler but for whatever reason still hasn't made it on the travel radar very much. That's where I meet them. At a very nice authentic Italian restaurant. They rent a car and check out a nearby dam where they go fishing, then they head up to Wat Chaloem Prakiat up on top of a limestone karst in the north of the province. A few days later, they catch a bus down to Tak and head into a national park there. After just over two weeks in Thailand, they fly to Malaysia where their first stop is Penang (yes, a touristy city, but you can escape the crowds quite easily).

Some countries are more suited to "off the beaten track" travel than others, but Thailand is definitely one country where you can have a fantastic time if you skip the done to death tourist haunts and check out some smaller, less well known provinces.

Thanks Mr Moto. To be honest I haven't done my research on Myanmar, i will look into it after your suggestion!
As i'v already done Thailand I will probably move on pretty quickly and start exploring the rest of SE Asia.

Im glad you say that lacapal, I'm not scared of the rain at all I just don't want it to put a dampener on the scenery!
If it wasn't for the weather I have read about I would probably leave in June and do 6 months, which I'm actually still half tempted to do...

Looking at Laos I think it would be ok to just stay further north (Luang Prabang, Vang Vieng, Vientiane )then fly to Vietnam and go from north- south and into Cambodia?

If anyone has any suggestions of some not to miss places i'd be greatfull! Im more of a jungle person than a beach person, iv found a couple of motor bike routes in north Thailand and Vietnam which look good!

Check out http://www.hobomaps.com/TravelChiangRai.html and http://www.hobomaps.com/TravelCKHX.html for travel info from Chiang Rai and Chiang Khong, including into Laos. The Hobomaps site in general has very good travel info for northern Laos. Getting from Chiang Rai to Luang Prabang the same day is a tall order, unless you take the first bus to Chiang Mai then fly or get to Huay Xai early and take a speed boat. Huay Xai (Laos border) to LP by bus is a good 12 hours, and agree with above Luang Namtha makes a good stopover for a day or two. The road quality varies and is twisty and hilly in places. Suggest to bring extra plastic bags for puking roadsick hilltribe kids, which is part of the classic Lao bus experience. As for Vientiane to Hanoi I would perhaps skip the nitty gritty bus from hell and just "haul ass" on a 1-hour flight. IMHO ;-)

This is all great to hear, especially the part about the lack of pervasive scams in Vietnam. I think the blogs on which I read about this were written by younger backpackers whose travels were focused in Vietnam's tourist centers (e.g., Sa Pa, Hanoi's Old Quarter, etc.). They may have generalized from their experiences in these places to the country and culture as a whole, which is unfair. I could care less about being overcharged by 5000 dong (~$0.25) for a plate of food. What I want to avoid is a culture, like I experienced in some parts of India a decade ago, where every other transaction turns into a big hassle, and many attempts to talk to someone disintegrate into an attempt to sell something. One thing that really appeals to me about Vietnam right now, beyond the wonderful scenery and back roads for motorbiking, is that the hotels seem like very good value, even relative to Indonesia.

What I'm coming to realize is that there are just too many great places to visit, suitable for my tastes, in the region for a single summer. I'll have to plan to do several trips to the region. I was also told today that there are thriving jazz and creative music scenes nowadays in Bangkok and Chiang Mai, which were not really well developed when I was there long ago, and I want to go check them out. But where to start? I'm not sure. It's great though to have many good options.

You are not going to get Certainty..

And I used to live in Bangkok and would do border runs to Cambo, my experience for mainland SE Asia in general is already posted up.

Why don't you reschedule your trip to November December early Jan of this coming year? That is the only time you will be assured of little rain and perfect weather to travel. By the end of Jan, the heat and smog have started to build so there is a window. Saying that the smog is building later this year in Chiang Mai because we have had unseasonable rains in December and then around Christmas and New Year’s. Nice as that cleans out the air and delays the build up. It’s the weather who could have predicted that huh

So, if anyone interested in "things to be spelt out in every tiny detail".
I just passed the border Thailand-Myanmar
The following are the steps for going from Thailand to Myanmar overland.

...0. First do the electronic visa for Myanmar on https://evisa.moip.gov.mm/ . I did the visa in afternoon and received it the morning after. The visa (as it happens for other e-visa) it's basically a paper that has be print out and presented at Myanmar immigration. On the visa letter is written that you need a train/flight out of Myanmar as well to present to the immigration but nobody at the Myanmar immigration asked that to me.

1.Take a bus to the Thai border town of Mae Sot (in Thailand). I took a minibus from Sukhotai but of course there are bus from Bangkok and other Thai cities as well.

Two2. The minibus in Mae Sot arrives to the bus terminal, about 7km from the border with Myanmar. At this point there are 2 alternatives: I'm being said that from Mae Sot I could take a 15 minutes walk to the market and from there take a songthaew(shared truck) for the 5/6Km left from the Mae Sot market to the border for 20 baht(0.60 dollars). Or: just take a scooter for 100 baht(around 3 dollars). I choose the second option because I felt that for 2.4 dollars less it was not worth the "sbattimento"(very interesting Italian slang word)

Three3.first pass Thai immigration. You give them the departure card (the one on the other side of the one with a stamp they gave you when you arrived), they take a picture of yourself and take your finger prints

Four4.walk over a bridge (the friendship bridge).

Five5.arrive at the Myanmar immigration. First they bring you to a room were 2 "nurse-like" people take you the temperature and put a sticker on the outside of your passport with written "quarantine section Myawaddy"(something like that). My temperature was 36.5. If you have 37.5 or more I guess they bring you to hospital...? Then another booth they give you a kind of arrival paper to fill in .Then a room with 2 immigration officers on a computer that take a picture of you and stamp the e-visa that you print out and they stamp your passport as well.

Six6. Then arrived in Myanmar,for changing your cash to local currency: look for some shop with tables and money counters machines outside. You can also buy a locale Burmese SIM card in some of them.

Seven7.Take a shared van for Mawlamyine: as it happens in other places (I.e. rural areas of China) you have to wait that there are at least 3-5 people for the shared vehicle to leave.
For other places like Yangon there are regular bus as well.

eight8. After passing Myanmar immigration, changing money and buying a local SIM card, it was around 1:30pm and I had to wait a couple of hours for the shared taxi to Mawnlamyine to get full and leave.

nine9. The street between Myawaddy border and Mawlamyine is still (as per March 2020) in construction, so, there is a looooot of dust and a lot of bumps and a lot of working trucks and machines that are slowing you down. The trip will take around 3 hours and half. We passed a couple of what (i guess) were police/immigration checkpoints on the way between Myawaddy border and Mawlamyine but nobody asked for my passport.

Cheers