If you are looking for something "formal", then I do not recommend a "casual" kilt. Don't get me wrong, I love casual kilts and the kiltmakers that make them. It's your criteria of "formal" that leads me to recommend Stillwater Kilts Standard. It's a terrific kilt for not a lot of money. I own two and I find it easy to dress them up or down. It's acrylic, but it's a mighty fine value and you also get to experience Jerry's Time Machine!