Comfortable ghillies can be worn day after day.

Saving that, I would suggest boots. Boots, hose full up or scrunched down, look great with a kilt unless you start wearing a tie, waistcoat, etc.

Boots are what I almost always wear with my kilt unless I'm going formal enough to warrant a jacket. I wear black, side-zip boots made for police, swat, etc. They are quick to break in, super comfortable, supportive, and engineered to be comfortable for 8-10 hours on your feet daily. Hiking boots will give you the same benefits, but usually only come in browns. I like my boots black, and zippered.

Hope this helps.