What you should do is Saigon (with one day beautiful organized excursion Cao Dai Temple of Tay Ninh + tCu Chi Tunnels), then the Mekong Delta Saigon-Cai Be-Ferry to An Binh Island (1 night in the excellent Phuong Nam Homestay in the vilalge of An Binh (+ if you wish, one day bicycle and boating in the island), then ferry An Bin-Vinh Long and bus VL-Can Tho (1 night), then Cai Rang Floating Market in the morning and bus CT-Rach Gia (1 night), then speed boat RG-Phu Quoc, return to Saigon by plane.

This said, beach PQ + beach Muine is a lot of beach. You should consider going by bus to beautiful Dalat, spend 3 days there (lots to visit !), then return to Saigon by bus or plane

What's wrong with lots of beaches? Many people, especially westerners from cold Europe travel halfway around the world just to spend time on the beach. Mui Ne isn't just a beach though, it has sand dunes like no others you'll find in SE Asia so it's quite unique in that sense. Whereas Phu Quoc is mainly just beaches with a little bit of jungle and waterfalls in the central part of the island. However, it's beaches are longer and sandier and with fewer rocks than say Thailand's Ko Chang, so I would recommend Phu Quoc over Ko Chang for that reason. Also, it has an airport located on the island making it easier to access. I am not aware of any flights to Phu Quoc from Singapore, but there are lots of domestic connections from Saigon.

a moped is not a scooter, and a moped licence is not a scooter/motorcycle licence. Mopeds are 50cc, scooter start at 100CC and are much faster. No mopeds in Thailand. You can rent scooters everywhere in Pai and usually they don't ask for an IDP, but if you get stopped it's your problem. If you make a dent it's your problem. Accident? your problem.
Not much traffic in Pai so that's easy. Good luck.

Indeed. These events are simply photo ops. The same happened on March 19 at the second Thai-Myanmar friendship bridge in Mae Sot. Prayut and Aung San Suu Kyi were there, but almost 2 months later, there is no indication of when the bridge will actually open.

I was there late last month and was allowed to drive across to the middle of the bridge and take pictures. I asked the first guard and he said that the bridge "might" open in May and when pressed further stated it will "definitely" open sometime this year. The second guard at the base of the bridge said it "should" open in May, but not really sure.

I wouldn't be surprised if the bridge still isn't open in 3 years from now, if the Lao-Myanmar friendship bridge is anything to go by. Ditto for the Thai-Cambodian train; could take a while before passenger services are actually started. In the meantime, one can take the train to the new border station, get off, get stamped out of Thailand, into Cambodia in the usual manner, then get on another train in Poipet and vice versa if heading in the other direction.

Certainly won't be very practical and will thus turn off many travelers, but this is the only option for now, if you want to catch the train between Bangkok and Phnom Penh.

With one whole week, it is possible to do both Chiang Mai and Krabi with a little flying. I would skip Kanchanaburi as it is not on the flying route.

PICTURE - Scenery in Pang Mapha area , Mae Hong Song province , west of Chiang Mai.

So what would an itinerary for a week be in Vietnam and a week in Thailand for instance. All they are doing is filling up their passport and ticking boxes and they will see little of each especially if wanting to do it on a budget

At the end of the day OP has to decide if they want to stretch the surface or see a bit more of fewer countries.

Well that is so easy. With a well established domestic flight network in both countries, it's easy to get around and get a taste of each place.

Everyone is different - some people want to see as much as possible in as little time as possible, others come for 2 weeks to laze just on one beach. Some people will find the latter too boring - don't get me wrong, I love beaches, but I would never spend 2 weeks just getting a tan on one beach. That's something Europeans like to do, but Asian tourists tend to have less time and prefer seeing more places in a limited time. Either way, everyone's tastes and circumstances are different.

Well what would an itinerary look likr for a week in Thailand and Vietnam? Geez...that's hard to answer not knowing what someone's tastes are but let's see here: 2 days in Bangkok, 2 days in Chiang Mai and 3 days in Hua Hin or even Krabi. Catch flights between these cities (could even do a triangular loop like Bangkok-Chiang Mai-Krabi-Bangkok catching direct flights between each of these cities).

In Vietnam, 2 days in the Mekong Delta, 3 days in Mui Ne or Nha Trang (Nha Trang is accessible by air, so that might be the better option) then 2 days in either Danang or Hanoi.

A traveler like the OP might consider spending all their time in each country in one geographic area to limit travel and then visit other areas/regions of that country on a future trip. For example, spend 7 days just in central Thailand (Bangkok, Ayuttaya, Hua Hin) and a week just in southern Vietnam (Ho Chi Minh, Mekong Delta and Mui Ne).

Aside from gap year backpackers, most tourists tend to spend only a week or two on vacation and seem to be quite satisfied with their travels. Many people like to leave something for next time, rather than "doing" a country by spending 3 months in each destination so they can see everything because they'll never be back again. I personally don't know anyone who thinks this way; most travelers consider making a repeat visit to a country they liked.

Haven't been to myanmar in awhile, is it possible to go from Tachilek to Mandalay by bus/motobike/car and beyond? Or, do you have to leave your passport at border and return to thailand via tachilek, thanks! Sorry for slightly ot.

I noticed you are traveling solo from other post, go to Mutmee Guesthouse and see if any other travelers want to join you and share the cost. Most of travelers staying there are friendly from my experience.

Now Mutmee bought back memories from on this board around 15 years ago.
At the time the owner was a westerner,who made some very positive and helpful contributions to this board. I was planning a trip,and was going to stay at that place. Never did sadly,but as I am going to Thailand monthly because of family working there I'm interested in exploring more during my visits.
What are your opinions of the place?