First the bad.
As STWW suggested on another thread, it would seem that they have stopped doing the 'fly thru' service from Udon. I have not managed to find any official statement saying that, but it no longer appears to be an option to book such a flight on their web-site.
A pity as it was quite a time saver on the outward leg, although not so much on the return.
The good(s).
Up until next Sunday they are offering up to 50% off normal prices on flights taken before February next year.
From June 9th. they are flying from DM direct to Da Nang in Vietnam. 1 flight a day, conveniently taking off at 10:10 am & returning into DM at 13:20.
I have just booked a return trip in November for 4,310 baht per person that includes 20 Kilos of luggage & seat selection.
The last time a went the cheapest choice was Air Asia to HCMC & then Da Nang via Vietnam Airways. That set me back just over 12,000 baht per person - so a large saving.
As an aside, I was going to use Lion Air as the cheap option between Udon & Bangkok. However they seem to have backed away from the cheap tag. Even booking today, their cheapest seats were no longer available for November.
It would have been 2,500 return per person. I returned to Air Asia & their up to 50% off deal..1,630 per person..