Years ago I remember seeing the wonderful red highland cows, especially concentrated in a few places. Are these cows just in random places, wherever the farmer happens to be grazing them, or are there areas where they are concentrated? This summer we will be driving only parts of the highlands--from St. Andrews to Glen Coe and possibly Loch Lomond. We can detour if there is an area where we would especially see them.
I remember seeing Highland Cows in Glen Lyon. You could explore it on your way from St. Andrews to Glencoe. The Glen is north and west of Loch Tay.
Also, check out the Highland Cattle Society breeder links. You can plot their locations on a map.
You may have several opportunities, but the only reliable one I know to suggest is the Culloden battlefield visitors' center.
Glamis Castle has had a herd since 1987 http://www.glamis-castle.co.uk/news_detail.cfm/news_ID/13/title/title=Garden
They are very cool beasties!.
There's a few on some of the National Trust properties.
Try anywhere on the West Coast - herds just happily wandering around ..... the calves are lovely ... they are pretty docile and used to people - not so common East and South. Also, in Ireland.
If you are referring to the funny, hairy cows - my best view of them was on my plate. Scottish beef is excellent. Although, I can't be sure what type of beef I was served and I didn't ask. The hairy cows are quite photogenic.
We walked through a herd of Scottish cows (shaggy reddish fur with big horns) past Tyndrum where the West Highland Way path goes under a railroad track if I recall correctly. They were big but didn't seem aggressive. That said we moved slowly and with caution. It didn't seem to be a good time to pull out the camera.
We were in the town of Diurinish near Plockton a few days ago. They are everywhere; on the road, in the yard, even lounging on the beach!