I'll probably rent a car as I'm planning to move around. Thanks !
It really depends on what you like - eg the wilderness, go up north to the real highlands and get over to Skye for scenery. Or some tourist landmarks like Inverness/Loch Ness and nearby Culloden centre for a bit of history. Edinburgh for the capital city - loads of things to do there. Try to go to a Highland Games - plenty of those around in summer. about 7 years ago
Basically a good round trip is up the west coast to Ullapool back down the the East via Inverness and Dundee.
Places to visit, assuming a start from Glasgow:-
Hill-house, Helensburgh. Rennie Macintosh's masterpiece, gives you a nice drive up the Clyde. Drive on - stop at the Loch Fynne Oyster bar for sea food as fresh and good as it can be. Drive on to Inveraray, visit the Jail or the Castle, both great. You now have a classic bit of road in front of you to Oban - one of those used in adverts and car shows, absolutely ace. Stay over in Oban and visit the Observatory. You can then either scuttle over to Mull from where you could take trips to Iona and Staffa (Fingals Cave), or carry on up the west coast into 'the Big Stuff'. I'd recommend statying in Glencoe rather than Fort William and getting you boots on, if you are reasonably fit. You've got choices of classic and spectacular hill-walks which are all miles better than trogging up the Ben. If you are fit do go over to Fort William and walk the Ring of Steal rather than the Ben; absolutely ace.
From there up through Torridon, again if you want to walk Slioch is a good one. The whole journey then is full of terrific country; mountains beaches and islands, and there are any number of diversions you could take, to the various islands and penninsulars, all of which are lovely. I'd recommend stopping in Gairloch, and visiting the tropical gardens at Inverewe.
On to Ullapool, stay there. Back to Inverness. Stop in Dundee and vist the Discovery, whcih is permanently moored there. Edinburgh and Glasgow both have plenty to enjoy, but generally Glasgow is better and less pricey for a night out. Stirling Castle too is well worth a visit.
The visitor Centre At New Lanark if you want a bit of industrial history in a beautiful setting that you won't get anywhere else in the world.
Further south Drumlanrig Castle is an amazing slice of british aristocratic priviliedge (thieving b's). Culzean Castle too, (a bit closer to the central belt).
Plan yourself an itinery, maybe with a few of those places and a distillery visit or two chucked in, come over and enjoy. about 7 years ago