I only ever wear the kilt with tweed daywear or with black argyll, black waistcoat and black necktie for evening events. Always with jacket and waistcoat, always with dress shirt and tie, always with a sporran (leather with belt for daywear, artificial fur from FreeRangers with chain for evening wear), always with hose, rarely with flashes, always with monk brogues or brogued boots depending on the weather conditions, and if a hat is needed I picked up a very nice RM balmoral in bottle green earlier this year.

However I wear ties, blazers, trousers, and suits year round whenever I'm not in work clothes, so my formality of dress while kilted is roughly the same as my usual (though I usually wear floral/paisley shirts, so being kilted is typically a step up for that reason alone as I'll pick a solid or tattersall).

I'm in Hamilton Ontario, so with the humid continental climate and my propensity to layer clothing I only wear the kilt in the cooler seasons; for staying cool in the heat (and avoiding the sun!) I stick to linen trousers.