I vote for comfy shoes. I have flat feet and heels are rough. Although, years ago I did see some lovely granny boots (about 8 inches tall) with low heels that looked really comfortable and very stylish. Of course, the shoes depend on the dress style. Which I think I've figured out. (I blame myself)
Naturally, I will wear whatever for ceremony and pictures and then switch to comfy later. And there is lots of time to shop.
As to how one deals with painful happiness? One deals. There are a lot of things even in the most happy circumstances that can cause emotional pain. The father's dance with the bride always gets me, no matter how happy I am for the couple. It will hurt me at my own wedding, but there isn't a damn thing I can do about it. Knowing what sets me off does allow me to compensate by taking bathroom breaks (at other people's weddings) or just doing something non-traditional (at my own). There will be no "giving away" at my wedding, either. Maybe an escort, depending. Although we actually discussed the scenario where each of the participants (couple and two witness, officiant) enters the sacred space from a different direction/point of the pentacle. Requires a lotta open space, though...
Life itself is bittersweet. Without the bitter, how would we know what sweetness is? People who always get what they want are never happy.