Citylink Explorer Pass or Train

You can buy it on line, but it is then mailed to you- allow 18 days for delivery, or just buy here on arrival, at a coach station.
To reserve a seat on line select your journey in the on line planner, then at the payment stage, select voucher, then enter your pass number.
Reservations are advised, but not essential.
It's a great way to get around free of advance train restrictions.
One suitcase is allowed, stowed by the driver in the hold, and one reasonable size carry on.
Book you accommodation first, then the coaches. If the coaches sell out, very rare, it will be at the last moment. You can more or less rely on last minute seat availability.
The coaches are modern, high quality and on many routes more frequent and as fast as the train.
The explorer pass is good value.

It depends on where you are going in Scotland.

As an example, between Fort William and Inverness, there is no train service. The bus is not a long distance coach but a regular service used by locals. You carry your bags with you and if I remember correctly there was a place to store my luggage. (It's been a few years.)

My suggestion would be to plan your route and then decide which is the best transportation option.

For day tours, take a look at Rabbies

When is your trip? While not as difficult as lodging in island towns accessible by bus, Oban is a very popular stop for those interested in the two- or three-island ferry trips to Mull/Iona/Staffa. I'd start exploring lodging options there immediately. One quick place to look is booking.com. If you prefer, you can use that website for research and then book directly with the hotel or B&B.

High-season demand greatly exceeds supply in accessible locations in that part of Scotland. Rates reflect that reality, and a few folks seem to have taken advantage of the situation, converting sub-standard rooms into places they rent out at inflated prices to people who perhaps neglected to read the reviews. That comment is based on what I observed when researching my own 2019 trip (though I think the situation was worse in Skye than in Oban). Read reviews carefully; those on booking.com are generally reliable.

Frank II is incorrect and out of date about the Fort William to Inverness coach.
It used to be part local bus and part coach until Stagecoach closed Fort William bus depot.
All routes in the area were taken over by Shiel Buses (a long standing local operator), who now operate the route for City link with coaches as stated, with holds for luggage. As a coach service it also serves local stops. They are the same vehicles as Shiel use on the Skye to Glasgow service.
There is also a vestigial route 17 part run a few times a day from Inverness to Drumnadrochit only with local buses, but the above applies to all City link sold and branded services, over the full route.

As my initial post was apparently mis-interpreted (or misread) as saying that Citylink only operate in competition with trains, they also operate to non-railway destinations such as

• Campbeltown (Kintyre) via Kennacraig (for Islay and Jura- scheduled to connect with all ferries) and Tayinloan (for the Isle of Gigha).

  • Glasgow to Uig via Fort William and Portree (for North Uist and Harris in the Outer Hebrides)- between Portree and Uig Stagecoach also run local services
  • Inverness to Ullapool for the ferry to Stornoway (Isle of Lewis). While also a local service (run with coaches) it's primary function is as a ferry connector, and the service will run early or late in the event of ferry disruption. Stagecoach also used to run a competing service bus to Ullapool- this is no longer the case. Note that if you are staying in Strathpeffer the timetables at the stops in the village last year said that the Ullapool coach stopped there. That has not been the case for several years, as it has been re-routed.
  • The Coach connection from Glasgow to Belfast also runs on to Stranraer.
  • On the Glasgow to Inverness route 2 buses a day connect through to/from London Victoria- and through tickets can be purchased through Megabus.

Note that Citylink also run a 24 hour a day service between Edinburgh and Glasgow, and (very new) a 24 hour a day service from Glasgow and Edinburgh to Aberdeen.

Stagecoach also run a high quality coach service (doubling as a local bus) from Aberdeen to Inverness (service 10), and an express
coach every hour from Glasgow to Dumfries.

Stagecoach also run the X99 service from Inverness to Scrabster (Thurso) for the Orkney Islands.

Between Glasgow/Edinburgh and Dundee there is also a company called Ember, who run electric coaches 24 hours a day.

Note that the route 10 from Aberdeen to Inverness has now become part of the Megabus network and renumbered as M96. It is still also a local service bus, but a lot faster than previously.
Other service enhancements for this summer include a near hourly service from Fort William to Inverness, and a new integrated service from Edinburgh to the Outer Hebrides - Harris or North Uist, depending on the day of the week. 0855 from Edinburgh, arriving back at Edinburgh at 2019. Coach to or from Uig connecting at Fort William then ferry. This also has connections at Perth from Aberdeen.
There is also now a daily service from Edinburgh airport to Oban, connecting at Tyndrum for Fort William.

Scottish Citylink, in conjunction with Megabus, are now running a Th, Fr, Sa and Sun bus from Glasgow to Southanpton overnight via Manchester, Birmingham, Oxford Parkway station, Newbury (for Highclere) and Winchester, returning next morning- ideal for cruise passengers and for the Cotswolds.
Also on Friday, Saturday and Sunday to Cardiff via Manchester, Cheltenham and Bristol, by day, returning overnight.
A very useful service for South Wales and Bath.
Fares on the Southampton route start from £25 and on the Cardiff route from £20