Thank you all, I really value your insights.
Almost all of you mention the heat and humidity. It is definitely a concern for me. My dh however keeps trying to convince me I'll be fine! So...it may be a matter of us trying it out and testing the hypothesis. I think the idea of early starts, a rest and then evenings out makes sense, and I do really want to VISIT that part of the world, but maybe a visit will rule it out as a retirement plan. Rosalyn, the idea of January for some cooler weather in parts of Vietnam makes it easier to enjoy our reconnaisance trip at least, thanks.
I have heard that Ecuador has highlands as you've mentioned Renee, though I've also heard altitude sickness is a real thing in Quito. I have heard that coastal Manta is moderate, but not sure how much I can depend on. Honestly I have been browsing so many climate charts they are blending together--I need to start a spreadsheet or something! Renee and Cala, I am glad to hear you speak favorably of the region. It seems to be a bit of a "black hole" with regard to people with experience! Not sure why so many people go to Asia and so few seem to go to South/Central America.
Suki, in Asia we have mostly discussed Thailand and Vietnam, and perhaps Malaysia. Laos and Cambodia rarely come up in the retirement conversations. I have definitely heard that Cambodia has a great culture and people. You are right, our first trip will be shorter than we'd like. (I get 4 wks vacay a year and it would kill me to use it all at once--I want to save a few days for Christmas at least.) So that's a big consideration. Do we do one country well, or a couple of countries lightly? I prefer "slow travel", settling in to a region to get to know daily life, but it is such a big trip to get there I also feel like we need to have a good look around. Vietnam is not a great choice for settling, with regard to making it easy for expats, but we have Vietnamese friends and love what we know of the culture.
I worked with some folks from Malaysia and have a strong interest in the country, but their human rights conditions are tough. I am straight but my kids aren't and while they won't be living with us, I don't know how comfortable I'd feel in a country that would imprison or whip my daughter because she has a girlfriend. I know SE Asia does not have the same level of protection that NA does, but at least Vietnam, Singapore and Thailand have some protections and recognitions.
Robert, the "Cameron Highlands" sound like they should be in Scotland, not Malaysia, lol. But it sounds lovely.
I also like the idea of Singapore as a gateway to SE Asia, as you suggest Robert. I am a little intimidated by the idea that I can't even look at the signs and street names and so on in Asia and know how I might pronouce it at the very least! Maybe that's silly, but I feel comfortable in Europe even when I don't speak the language because it's easy to learn and recognize words. Every Singaporean I've ever met speaks flawless English and I know it is an offical language there, which I find reassuring.
Will definitely check out Fodor's forums too, thanks for the suggestion.