The ideal way to do such a trip is towing a caravan, so that you can stop off virtually wherever you like and take time out to explore the area leaving the caravan parked up. You don't even need to buy a caravan if you have never done this sort of thing before because you can rent one. Just look online for touring caravan hire and you can see a range of vans, one of which is sure to suit your needs providing you have a reasonable sized car able to tow a small touring van. Such a set-up gives you complete freedom to exlplore the wonderful rugged scenery of Scotland.
Take the west coast for example. Here you find dramatic cliffs and coastal scenery north of Glasgow with some unspoilt islands off the coast unchanged since the mists of time. Inland there are historic castles, lochs and glens, and mountains which are often capped with snow. There is Glen Coe, for example, famous for the battle between the MacDonalds and the Earl of Argyle's regiment in 1692. This a superb area for rock climbing or just walking in the hills, breathing air, fresh as only mountain air can be.
There is the picture postcard village of Invararay on the banks of Loch Fyne, and an 18th century castle which was the home of the Duke of Argyle. Oban has a whisky distillery and several stunning castles nearby, like Dunstaffnage Castle at Loch Etive.
There is a lovely road from Oban to Fort William following the edge of Loch Linnhe, taking you into the Scottish Highlands at the foot of Britain's highest mountain, Ben Nevis. All around here the scenery is stunning with mountain views, valleys, and moors, so if you have the time to explore it is well worth it as you could scarcely find better scenery anywhere in the world, with craggy peaks but also lush green hillsides and valleys. The area must be unique, and is a haven for much that remains of Britain's wild life including deer and rare predatory birds.
From this area you can circle back south towards Loch Lomond which, of course is a beautifully romantic place with peaceful views across the water and the ideal spot to wind down after the adventures in the mountains.
Caravan touring is increasingly popular and rightly so, since you don't have to book hotels ahead or worry about finding one en route when you're tired after a day's drive. Modern touring caravans bely their size, small yet offering a very comfortable, almost luxurious accomodation in many cases, and at much less cost to hire than you would pay for a week or two at hotels.