I want you to describe it beautifully!!!!!!

The wedding would be at cross academy. Zero would be companies about it but stops once he sees Yuki. Basically a sweet wedding all decorated by Yukis dad and toga Yagari would be zeros best man. Sayorii would be Yukis maid of honor and happy because she always wanted them together.

I think it'd be simple and sweet, despite many people's attempts to make it more dramatic or complicated (people saying her pureblood rank means that she'd have to have a huge wedding etc). Maybe they'd even end up eloping.

For some reason I think maybe they'd have an outdoor wedding - but maybe that's my own preference.

I agree that Sayori would be maid of honour/bridesmaid. Maybe Kaito as a best man? He's closer to Zero's age after all. Kaien would insist upon giving Yuuki away.

Random Zeki wedding fanart