Southeast Asia forum

I know it gets done a lot on here, so apologies for adding another route suggestion, but really I'm just looking for a bit of encouragement or reassurance. This is also the first time I will have written this out to be honest, so it's kind of soothing to get it down in words. So here's my vague probable route:
Fly into Bangkok on September 4th on a 60 day visa. Now, I'm thinking 60 days is quite a long time, so I'm not really in any rush in Thailand. Saying that, I don't plan on travelling far south of Bangkok, more so heading East/North-East, before ambling across to Chiang Mai and the rest of North Thailand. I figure I'll take it as it comes with 60 days to play with.
Head into North Laos on a 30 day visa, wing it around the north before heading down to Vientiane, and then downwards into the south, before hopping on into Cambodia.
Another 30 days in Cambodia, arcing West towards Siem Reap, then East to Phnom Penh. Cambodia is the main mystery really, in that I see it as being the country wherein there will be the least amount of travel, so uncertain about what I'll be doing there until I get there and see what's on offer.
Head on into Veitnam and straight to Hoi Chi Minh on another 30 day visa before embarking on the long journey north to Ha Noi where my trip will hopefully end in a flight to New Zealand.
Like I said, just a vague description of my planned route really. If anybody can see any glaring mistakes or has any opinions on differing routes I'd love to hear them. The only question I can think of really would be, would 60 days in Thailand be long enough to head south towards Phuket and that, or would the recommendation be to leave it out and see more of the bulk of Thailand?

Sorry about the long winded essay you just had to endure. A lot of it is just for my piece of mind. Cheers for reading anyway, would love to hear your comments.