What should i wear to a golf club wedding?

What should i wear to a golf club wedding?
My boyfriend is the best man at his sister's wedding.Taylormade Rocketballz RBZ Irons It is outside at a golf club. What should i wear as his girlfriend attending with him? also, any ideas for the rehersal dinner the night before?

I've been to 6 weddings and receptions at golf courses. a summer dress is very acceptable. the most important thing to remember though, is since the wedding is outside wear a slip if you are wearing a light colored dress,Titleist Ap2 712 Irons or everyone will see your undies. also, try not to wear spike heals, more than likely you'll be walking through a lot of grass, you can't look graceful in heels in grass. also, i've seen a lot of people wear sunglasses, i personally think it's a bit tacky looking, but i'm not 100% sure about the etiquette on this.