Are you sure those V and W fares earn mileage? I thought G,V,W were not eligible for mileage accrual. For a while they earned 50% when credited to Aeroplan but now it's zero, maybe it's different for Thai.

I find that Thai's prices don't change as much compared to AirAsia. The real advantage to AirAsia is if you know your travel plans well in advance or you can be flexible. I have several BKK-CNX and back trips booked right now, some O/W and one round trip. The round trip was 567baht and the O/W were all around 300baht depending on if I have luggage or pre-selected a seat. I like AirAsia, so to get a flight for $10 is just a bonus for me.

For flights way in the future I like AirAsia's Red Alert emails to advise you of the promotions, but for last minute stuff I am quite happy to fly Thai.