There are a few folks on here from Scotland, and can meet up depending on what you are doing, or you might want to call in to see some on your way depending on travel arrangements.
Edinburgh is an excellent place for a short stay (assuming you can afford the hotel cost!) as it has lots to do and a good range of historic buildings. Glasgow is also a good place to visit, has more of an industrial/trade history compared to Edinburgh (was more government/banking/etc) and also a wide range of touristy stuff to see and place to eat.
The other significant cities going north (Dundee, Aberdeen, Inverness) are all OK but a step down in terms of tourism.
However, one aspect that is worth doing as a counter-point to the cities is a visit to some of the highlands for the scenery. The A9 road (or taking the train) north from Perth to Inverness gives you a good view, but its a tedious road at times and also a bit dangerous as it flips from single carriageway to dual carriageway (with the opposite pair invisible at times) multiple times making overtaking, etc, a danger. Add to that lots of obscure junctions and you can see why its high accident rate has been a sore point for duelling for years.
Of course many other scenic options depending on your time, areas of interest, and itinerary, are available. The west highland rail from Glasgow to Mallaig is another good option, but you really need to stay over as not practical to go there and back in one day.
Weather is always unpredictable, assume any of the 4 seasons (possibly more than one) will occur on any given day!