Modest evening dresses in floor length are a thoughtful, universally flattering choice for formal wedding guests
According to Conways hypothesis, those up in the night are used to artificial lighting which has more reddish light in it, and thus their brains are accustomed to correcting from reddish illumination, which shows the dress as black and blue, while those who are more exposed to working in sunlight/daytime would see gold and white because their brain processes out the blueish light
If you do wear jeans, choose a dark, tailored pair without distressing and dress them up with a silk blouse, statement jewellery, and heeled boots or elegant flats
Or you can wear her as your night-out outfit!
Also, avoiding white is a bonus
I love pairing a sequin bottom with a simple top, or vice versa, so the sequins can shine on their own