Hi so I am of the opposite opinion. Don't go to Hoi An. It is just so busy now, it is almost like a Disneyland. So many people blocking the streets. It is yes a beautiful location but far too many people now for it's streets.
Hue is amazing and there is ample to see in and around Hue.
But if you do want to get to Hoi An, train to Da Nang (sit on the left going south for nice sea views) and then take a local bus. It is all very simple, especially if you do not have luggage.

