We will be in Edinburgh in June, and want to minimize driving. How is the train trip from Edinburgh to Oban? Scenic? Pick up car in Glasgow and drive, or train to Oban then rent car?
What are your plans for a car from Oban onwards ? No sense in picking up the car in Glasgow , you can pick it up in Edinburgh and drive direct . If you want to start behind the wheel from Oban , the train from Waverly to Oban via Glasgow Queen St. is 4 hours .
Most of the train trip is marked as scenic on my old BritRail map, starting from Helensburgh up to Oban. See also http://www.scotrail.co.uk/discover_whl.
Got our first experience driving On The Left in Scotland this past August. The roads are narrow by American standards, and you sometimes have sheep and other obstacles to contend with, including other tourists who aren't used to driving on the left (and sometimes in their own French, Italian, Belgian, or German cars, ferried across to Scotland, with the steering wheel on the "wrong" side!), so that may be what you're thinking about in minimizing driving. We made it without making any insurance claims, but there were a few hairy moments.
You may already be thinking this, but in any big city like Edinburgh or Glasgow, if you can pick up your rental car on the outskirts of town and not in the congested city center, life will be easier. You may need to take a taxi to get to that outlying rental location.
You'll have more choice if you pick up your rental car in either Edinburgh or Glasgow. The drive to Oban is not bad from either location. From Edinburgh pick up the car at the airport. Via Michelin's default route has you going through Stirling and then up through Doune--where Outlander and Monty Python's Holy Grail were both filmed--skirting the edge of the Trossachs and across to Oban. They suggest three hours for the trip. I bet it's closer to four by the time you throw in stops and a few missteps--we all have them and I view them as part of the journey. If visiting Stirling is on your list then you could decide to pick up your car there and head west.
Alternatively, you could take a bus--or the train, but the train goes downtown and you need to catch a bus to the airport. It's easy, but one more stage--to Glasgow Airport. The car trip is shorter and different. It will take you up the west coast of Loch Lomond. Do plan on stopping to take in the Loch. I think that Luss is a good place to do this.
Either of these routes will work. The A82 can be busy, but not so busy that it's worrisome. The roads that you are taking to Oban are all A Roads and so are not the small winding roads of the north that are single land roads with passing places. When you do get to the single-track roads, follow the rules of the road and you'll do fine. I don't know where you are from, but the really bad traffic roads are the ones in area between Edinburgh and Glasgow. Then there is the A9 which is the main road north to Inverness. It tends to have a lot of traffic and you need to pay attention. But it's no NYC or LA or Chicago. And it's also not like driving on to Cape Cod in the summer time where it's wall to wall cars.