Hal,

I take what you mean to be something like wearing yoru kilt with a nice button-down shirt with a collar, with or without a tie, maybe with a tweed jacket, correct? Nice looking, bordering on the semi-formal, but not really formal.

In that case, I'd agree with the person who said to wear shoes that match yoru sporran and belt. I, personally, would wear a brown belt and sporran in this situation, and brown shoes to match. But if I were wearing black, I'd make sure my black shoes were more of the dress-casual style -- nothing that would look like it ought to be worn with a tux, or else it would look out of place with the rest of the outfit.

Aye,
Matt