What are the best visa options for expats over 50 planning to split their time between Thailand, the US, and the UK?

If you plan to leave 800,000 baht in the bank, make sure that your marriage certificate has all the necessary endorsements needed (so that one of you can be a dependent instead of both needing to meet requirements.

A few things first:

Having a condo means absolutely nothing towards your ability to stay in Thailand.

If your wife will be working online, just pretend she's not working. Don't ask don't tell.

Neither the US embassy or the UK embassy provide certificate of income, so you cannot use proof of income for your visa in Thailand.

I'd say you have 3 options:

1) LTR. Look to see if you qualify for one of the LTR visas. If you do, it will make your life easy as it's a 10 year visa split into 2 5-year stamps. You'll be able to come and go as you please and will never have to interact with immigration after you get your LTR since you'll be leaving before you are in Thailand for 1 year which is when you would have to report that you've been in the country for that long. Your first time interacting with immigration would be approaching year 5 when you need to apply for your 2nd 5-year stamp from the BOI. More information here:

2) Non-OA retirement visa. This visa is a 1-year multiple entry visa that you get by showing money in your home country, and an insurance policy for $100,000 USD. This means you won't be required to lock money away in a Thai bank account. You can come and go as many times as you want during the 1 year and each time you enter the country you will be stamped in for 1 year (or until the end of your insurance).

If you enter right before the visa expires and get a fresh insurance policy, you can basically get 2 years out of this before you need to return home (which you'll be doing already) and apply for a new OA visa.

3) Multiple-Entry tourist visa (METV). This visa is valid for 6 months and each time you enter Thailand you will be stamped in for 60 days, and you can apply once for a 30 day extension each time you enter. So you'll be able to get 90 days, and then you'd have to leave and re-enter to get another 60 days which you can extend again for 30 days. Again with this one if you leave and re-enter right before the visa expires, you can get up to 9 months in Thailand (more than you need). If you're already planning on doing some traveling around the region then you won't even have to make a special trip to get extra time.

All of these will give you the time you are looking for. If you qualify for LTR I'd go for that since it's currently the most beneficial. Otherwise the METV will likely do what you want without having to deal with insurance or proof of money.

You can stay on the retirement visa although it does not allow you to work. Best to keep quiet on the online work. Spending just 4mths in Thailand you could get a 60 day tourist visa extend for 30 days take a trip to somewhere nearby and then get another 30 days.