In what order should my wedding party line up in - shortest to tallest or by order of importance

Firstly I wouldn’t recommend ordering by importance, as you don’t want your party to feel like the closer they are to you in line, the more important they are to you.

Secondly the reason for ordering by height is purely for aesthetics, so that at the end of the day your photos look great in your wedding album.

So to answer your question “In what order should my wedding party line up in”, I would say do both! For practical purposes, have your MOH closest to you as she needs to perform duties during the ceremony and you will require her to be in close quarters with you, then order the rest of your wedding party by height, problem solved.