Thought I could help the guys out since I am just a few months removed from my ceremony.
Bottoms: chinos, khakis, or suit pants. For the love of all that is holy...make sure they fit. No blown out asses, scrunching (on the ankle), or wide legs. At my ceremony, only a handful of guys wore actual suit pants. Fit of pant > type of pant.
-colors: navy, khaki, black, gray/charcoal
Tops: dress shirt (w/tie)
-shirt colors: light blue, gray, and white are most prevalent
Shoes: anything leather. I saw chukkas, chelsea boots, desert boots, wingtips, etc. Just make sure it looks good. Your shoes must match your belt (a hard concept for some).