We were on this same basic cruise this past September.
Edinburgh we missed because of the Queen's funeral but had been before where we did the Royal Mile walking tour. I remember it as being interesting.
Invergordon we did the Cawdor Castle and Culloden Battlefield tour. Castle was a gem with beautiful gardens. The battlefield is just a field with some flags showing where each side was, but our guide's commentary made history come to life. If you are an Outlander fan you will imagine Jamie riding his horse into battle😉 By the way, our guideDonald was one of the best we have had on any tour, Regent or not.
In Kirkwall the archeological wonders tour should not be missed. Skara Brae is fascinating.
Ullapool is a cute little town in its own right. We did the Knockan Crag hike and discovered our guide was to be the same Donald as we had in Invergordon. The hike itself is not for everyone, narrow, rocky, steep trail that was often on the edge of a cliff. Some people apparently did not read enough of the description and wore flimsy sneakers instead of the sturdy shoes recommended. If you like geology you will be fascinated as you will see where the theory of plate tectonics originated. Since Donald was at one time the head geologist of the Highlands we had expert commentary. Even if you don't like geology the scenery is gorgeous.
From Killybegs we did the Wild Sliabh Liag cliffs.It is mostly a see-it-yourself place though there is commentary on the bus ride there. Our guide on this tour was a dud, providing nothing useful. He wasn't even sure whether the tea stop should be before or after the cliffs. The cliffs themselves are beautiful, but it was very windy there. You are given about 45 minutes to wander on your own which a lot of people were not happy about. We loved it and hiked quite a way up the cliffside.
Having been to Belfast a couple of times before we had done the main tours. We opted for the Traditional Irish Music Tour. A lot of fun visiting several pubs and hearing the music.
In Waterford we did the walking tour. Found the tour mildly interesting.