I agree with this op.
If they are your style, I think the coral one is pretty (the green doesn't look very summery to me; its a bit dreary) but if they aren't your style, I don't think you need to feel it's necessary to go in "MOB Costume."
Especially if it's informal, go in what you feel like yourself in - or yourself on a special day. These to me don't sing Nobody's Child wearers.
Why not post a photo of the outfit you feel best in, and we can work from that to something for a special day. Sometimes I think people go as "someone else" when they have to be MOB!