Everyone tells you Scotland needs a car. It doesn't. The Highlands are threaded by trains and Citylink coaches that stop at nearly every place you actually want to be, and letting someone else drive means you get to watch the country go past — which, in Scotland, is the whole point. Seven to ten days covers this loop; budget 55-75 GBP a day with hostel dorms (Hostelling Scotland and independents, 20-30 GBP) and supermarket lunches.
Edinburgh
Start with two days in the capital. Skip the tartan shops on the Royal Mile and do the free things that are better anyway: climb Arthur's Seat at sunrise — a genuine extinct volcano in the middle of the city, 45 minutes up, the Firth of Forth silver below you — then wander the closes and stairways of the Old Town, the National Museum (free), and Stockbridge for coffee and charity-shop book hunting. The castle is 20 GBP; the view from Calton Hill is nothing. If August, the Fringe swallows the city whole; book beds months out or aim for another month entirely.
North to Inverness
The train from Edinburgh to Inverness takes three and a half hours (from about 20 GBP booked ahead) and crosses the Cairngorms' shoulder via Aviemore. Inverness itself is a night's stop more than a destination — riverside walk, a proper pub session at Hootananny with fiddle players stacked in the corner — but it is the hinge of the Highlands. If Loch Ness matters to you, the bus down the lochside to Urquhart Castle is easy; we would rather spend the afternoon at Culloden battlefield, whose bleak moor and superb visitor centre explain half of subsequent Scottish history.
Skye
Citylink coach 917 runs Inverness to Portree in about three and a half hours (around 25 GBP), down Loch Ness and over to Kyle of Lochalsh, where the bridge jumps to the island. Base yourself in Portree, the pastel-harboured capital. Skye's problem is popularity; solve it with early starts and the local bus network plus the odd hitch — Skye drivers still stop.
The Old Man of Storr walk (45 minutes up) before 8am is one of the great short hikes anywhere: black pinnacles, the sea, the mainland mountains stacked behind. Further north, the Quiraing's landslip amphitheatre and the clifftop at Kilt Rock fill a day; the Fairy Pools another. Pack for four seasons per hour, and buy midge repellent in summer — the midges are not a joke, they are a weather system.
Fort William and Glencoe
The 915/916 coach south to Fort William hugs Loch Cluanie and Loch Lochy for two scenic hours. Fort William is a plain town in an extraordinary spot: Ben Nevis rises straight behind it, and the mountain track up the UK's highest summit (1,345 m) is a hard but non-technical 7-8 hour day in good conditions — check the forecast, carry map and layers, and turn back without shame; the plateau kills the casual.
Twenty minutes further south, Glencoe might be the most dramatic roadside scenery in Britain — buttressed volcanic walls, the Three Sisters, light changing by the minute. Stay at the Glencoe village hostel or wild camp responsibly (legal in Scotland under the access code) and walk the Lost Valley, a hanging glen where the MacDonalds once hid rustled cattle.
The West Highland Line home
Finish with the payoff: the train from Fort William to Glasgow, three and three-quarter hours across Rannoch Moor, a boggy, lochan-scattered wilderness the road never touches. Corrour station, stranded in the middle of it, is where the Trainspotting crew got off to not appreciate nature. Sit on the left side heading south, buy tea from the trolley, and watch Britain empty out and refill. Glasgow deserves a final night — friendlier than Edinburgh, better music, cheaper pints.
Go May-June or September: long light, fewer coaches, fewer midges. Book beds on Skye well ahead in any month.