What is the best visa option for a family of four relocating to Thailand for at least two years?

you cant travel if kids are going to school

It seems as if you keep reposting this.

yes

If the kids are enrolled before you get here then ask the school for the documents you need to apply for their Ed visa. One parent per child can apply for a Non O based on being a guardian.

That will give you 3 months on arrival. The kids can get a year extension with no requirements other than documents from the school and some copies of passports.

You’d have to bank 500k in a Thai bank (per parent) for at least one month prior to applying for a year extension based on being a guardian.

If they’re not enrolled before you get here you can enter exempt and enroll them in the school you prefer. They’ll get the Ed visa. Once they’re on the year extension you’d apply for a non O from a nearby embassy (you can’t apply in country) and after the three months extend using the finances as above.