Hoi An is the part of Vietnam I’m most looking forward to - the lantern-lit old town, the slower pace, maybe a bit of tailoring. Some tours only stop for a day there while others give you two or three nights, and I can’t tell if the longer stay is worth choosing the trip around. Did you wish you’d had more time in Hoi An, or was a day plenty?
Hoi An is such a nice and lovely place, I’ve been there once (3 years ago) for a few days. I say: one day is not enough. It’s possible in Hoi An to have clothing custom-made. They’re very good!