It's a very scenic area, and you have choices in your route. You need to do some research, eg, undiscoveredScotland, and decide which route.
The main road, the A82, is stunning in parts, eg Loch Lomondside and Glencoe, but most of it and side roads are a joy.
You could go via Inverary, over the Rest and Be Thankful pass, but this might depend if you are in thecregion again?
Nice places to stop for a stroll on the banks of Loch Lomond - try Firkin Point. Inveraray good for a pit stop.
Btw, why is this question in the Eriskay forum!
Not sure how it ended up in this forum...most likely user error!
I would stop off at Luss for a coffee/tea and scones or a cake (I can't resist them, ever) in The Coachhouse and then stroll down the tiny main street to Loch Lomond's shore and admire Luss's situation with the hills behind.
Then cut through at Tarbert and make for Inveraray via , as others have mentioned, the Rest and Be Thankful Pass.Inveraray Castle is well worth a visit.Loch Fyne Oyster Bar (just before the town) or The George Hotel/Inn are worth considering for lunch.If you don't want to fork out too much, the little Garden Centre next door to the Oyster Bar does good soup and home - baking.
Kilchurn Castle on Loch Awe is well worth the stroll out to see(free).Just look out for the rather hidden parking off the main road.
St Conan's Kirk not far beyond here is also worth a visit - gorgeous.
Dunollie and Dunstaffnage Castles are also just outside Oban.
Look out for sea eagles on that last stretch of road to Oban - one literally flew over our car on our last trip there a couple of months ago!