Yep, definitely heels (and this is from a non-heel wearer) but I'd wear flats to the ceremony to save your feet because hanging around outside/inside is what will kill your feet. You won't notice after a couple of drinks and a bit of a dance.

I'd go bronze or neutral actually. Neutral ie. cream/beige will elongate the leg. Definitely gladiator heels. Chunky heels are more comfortable.