I agree that the picture McMurdo votes for is the most impressive combined with his ideas. I vote however, for the first picture (because it's your new kilt! you should wear it ). with a charcoal or dark red tie. In the case of the dark red tie I'd consider a black or charcoal shirt. (if you have any of what I mention. T'is just ideas). without the waistcoat (looks good - but for this occasion which is 'not too formal' I'd leave the waistcoat out). You might want to consider less formal shoes, but I think those look awesome so I wouldn't change em myself.

Hope t'is of any help

Daniel