Glasgow is another big city. Although very different in feel and culture to Edinburgh, it isn’t allowing you to see much of the Scottish countryside, and I would discount on those grounds. It is easy to do from Edinburgh on the train.
Are you looking for a day trip by coach or are you thinking if hiring a car?
If looking for a coach trip, Rabbies, Timberbush and Hairy Coo are all well regarded on this forum.
Read the itinerary carefully and understand the difference between ‘passing’, (usually at a distance on the by pass) seeing (seen through the window when passing - as long as you are on the right side of the coach...), stopping (usually a short stop for toilets and a photograph) and visiting when you actually spend a reasonable amount of time somewhere - long enough for the photo, toilets, coffee or lunch and possibly a short visit to the attraction...
Sorry if that sounds a bit dismissive - it isn’t meant to be, but can mean the difference between a good coach trip and a disappointing one. Also check out the size of the coach. If it is a big one, it will take so much longer for everyone to get through the toilets. Smaller coaches are preferable.
Glencoe and the Highlands is going to mean a long time spent admiring Scotland through a window. I would discount this one and look for somewhere which doesn’t involve as much driving.
St Andrews is a delightful sea side town with a ruined castle and cathedral as well as the golf courses and university. It makes a nice day out with a drive through the fishing villages along the Fife coast, or a trip to Falkirk Palace, a popular place with film makers.
The Falkirk Wheel (particularly if it also included a boat trip), and the Kelpies are popular. I know Loch Lomond is popular with visitors although I’ve always found it busy . Also when driving along the A82, views of the loch are restricted by trees. Stirling Castle is great, and I know many people say it is better than Edinburgh Castle. Do one, but don’t waste time doing both.
If you are planning on hiring a car for the day, then have a look at the different suggestions for car tours on the Undiscovered Scotland website. Several can be combined - eg Sterling, Dunfermline with Falkland and St Andrews. Also the Border Abbeys with Selkirk and Langholm.