Hmm... would you already be in night make up and with the dress for the dinner banquet already? If your dinner is right after then it might be troublesome to be wearing a different dress and then changing into the one for your march in. Your make up might not match too.
I already factored in time for the dress change. 6pm solemnisation and 7pm dinner. Make up can just touch up heavier for the banquet. If just solely based on rom alone, thinking of I should go for a long or short dress
Then it depends on the rom place. For garden setting, personally I'd prefer long flowy dress rather than something poofy. But both can work la, just depends on the look/feel you wanna have for your rom.