Hello /fellow travellers!

I am finalizing my plans for a vacation in SE Asia for this August, and have one final itinerary question. First, my itenerary is currently as follows

2 days Hanoi
2 night/3 day Halong Bay cruise (one night spent on Cat Ba Island)
3 day/2 night trek in Sapa.
1 additional day in Hanoi
4 days in Hoi An(?)
2 days in Saigon
4 days in Siem Reap
2 days in Bangkok(?)
1 night layover in Hong Kong.

I know I want to get a couple suits/shirts made while in SE Asia, and give it enough time to be done right, but Ive heard cheap tailoring is very findable in both Hoi An and Bangkok. For those of you who have spent time in both, given an interest in tailoring, would you spend the 4 days in Hoi An, or would you tack extra time onto Bangkok?