My suggestion is to go very, very chic. Stay away from anything trendy or flashy (I know you won't wear anything frumpy!) For the casual evening at the dive bar, most of the other women will probably be showing off their recent 25-lb weight loss in too-tight designer jeans and far too skimpy little tops. Wear something that makes you feel confident and self assured. Bump up the sophistication factor in a pair of wide legged linen trousers, a gorgeous top, funky jacket, strappy sandals and an elegant little bag. Your sophisticated style will make you a standout.
For the afternoon of golf, a knee-length cotton skirt (no shorter), sleeveless polo shirt and lightweight cashmere sweater (in case the weather turns) are just the ticket. If skirts are not your style, you could substitute a pair of bermudas or crops. If you don't have golf shoes, a pair of canvas skimmers will work fine. Leave off the jewelry; it just gets in the way. Don't forget a pair of stylish sunglasses, and use plenty of sunscreen!
For the formal dinner, you can never go wrong with the classic LBD. However, most of the other women will probably be thinking the same thing, so you may want to be a little more bold here, with either a great pattern or a vibrant color. If you have great arms, go with something sleeveless. If you choose a halter-neck style, don't go too plunging or too bare (chic and sophisticated, remember!) A great pair of sassy skyscrapers, a unique bracelet for bling and a really, really fabulous handbag (you know all the other women will be checking out handbags and jewelry!)