We flew today with ThainAir/ Air Canada to Tokyo and then Vancouver. Our plane leftv at 7:30 am. We got to the airport just before 5. There was a big lineup at checkin. After that we breezed thru Security and had a good 1.5 hrs to spare. In summary 3 hours would give you a comfortable pace.
Thanks Ally. Yes. I will take your advice. I've travelled years ago to Singapore and for sure I have find them bot to be laissez-faire. We'll do the flight to Bkk and/or get my wife's Passport renewed in Canada.