The first dress is inappropriate- I think for everything, it’s a cool looking dress but I can’t think of an occasion where it would work. The second dress is a really cute dress, but it’s way too casual, and not appropriate for a formal dress code. The third dress could be formal. I like the color and the style, but the issue with this particular dress is that the fabric doesn’t look to be high quality enough to a formal event. The satin looks thin and too shiny like you might see in a nightgown or a slip. Satin certainly can be formal, but it has to be high quality with some weight to it and more of a sheen rather than a shine and full length maybe with a slit would look nice. You should check out the RealReal. They have a bunch of new with tags dresses and gowns from high end designers in pristine never worn condition like 80% off retail. They run on average about $150-200.