Thanks, ExXB. Have now booked Emirates with a stopover in Dubai. I really hope the hold baggage is going through to BKK, that will make life a lot easier if I just have cabin baggage. We ended up in economy, but six hours at a time is doable, and we've booked a reasonable hotel. Son is meeting us in Bangkok, whole reason for the trip is to see his offspring after all. He can sort out the rest of the journey
Now to arrange the house sitters. Probably the hardest job.