First time to Scotland, can you check the itinerary to see if it's reasonable?

Anytime you fly someplace, even if it’s a short flight and you are efficient, that pretty much consumes most of the day. Same is true for flying away from someplace. Really most of your days would be spent getting to, being at, and getting away from airports. So going someplace for a single night, then getting up and flying back seems like a very poor choice to me.

Shetland is lovely, magical, and the kind of place one needs some time to savor and appreciate. To me it would be a tragedy to go there for a “drive by” of just a couple of hours of usable time (and that’s all your plan would get you). We spent about 10 days there last summer, loved it, and didn’t get to all the places we had hoped to see.

I would urge you to reconsider.

If Shetland is a must do for your friend, why not lean into it? Where in Shetland is grandpa from? Do a bit of research on Shetland. You could spend weeks there.

Start with a few days in Edinburgh, fly to the Shetlands for several days, fly to Glasgow, pick up rental car to explore the Highlands for a few days before ending in Glasgow.

3 nts Edinburgh
4 nts Shetland
2 nts Ft. William for the Jacobite train
1 nt Pitlochry or somewhere else of interest
3 nts Glasgow

IMO, Skye really isn't worth the effort for only 1 night. You need a minimum of 2 nights.

Any chance you could fly into Edinburgh and back home from Glasgow?

As regards flying to Shetland for one day the big flaw is that Sumburgh is an airport in the middle of the North Atlantic where weather can change like the flick of a switch.
It can and does get socked in by wind especially. It is far from unknown to take off bound for Sumburgh, then the airport closes and they have to turn back mid flight. Likewise you might get in that morning, but be unable to get back that evening.
Likewise Shetland is a much bigger place than you might think.
It is about an hour from landing to getting to Lerwick (the 'Capital' of Shetland/the county of Zetland), then another hour to the far end of the Mainland.
Depending on where your grandfather was born it may not be physically possible to connect to the relevant island and back in the same day by internal ferry from the top of Mainland (in some cases two domestic ferries). Each island is quite distinctive as well, so if grandfather was from Unst (say) or Out Skerries or Fair Isle (as 3 examples) then just getting to Lerwick hasn't accomplished much in my eyes.

As regards the Jacobite Steam Train- be aware that you will be travelling in modern train cars (not Harry Potter-esque old cars, which can no longer be used for safety reasons) and for much of this summer (2025) the steam engines were replaced by diesel engines due to the fire risk.
You are far better travelling exactly the same tracks on the normal Scotrail service train, getting the lunchtime train out (a better time anyway if starting from Inverness). All at a fraction of the price. And you get more time in Mallaig.
Rather than staying in Fort William that night you could continue to Skye the same evening, arriving late, but then you get the whole of next day on Skye.

If you want the old style train cars and pretty much guaranteed steam then the Strathspey Railway from Aviemore would be the way better choice if staying in Aviemore.

Both itineraries are rushed - even without Shetland, or Skye and the Jacobite train...

You won't want or need a car in either Edinburgh or Glasgow as public transport is so good and parking a nightmare as well as expensive. Hire when you leave Edinburgh and drop off when you arrive in Glasgow. +(Use rthe train tyo get back to Edinburgh on the last day.)

I think you may be underestimating the time needed to see the different places. Driving in Scotland is very different to in Canada and it will take a lot longer to cover the distance than you might expect. You are also allocating a lot of time to cities (Edinburgh, Glasgow, Inverness) rather than the countryside.

Much as I like Inverness, what are you expectations and what are you planning to do there to fill the two full days?

Either Shetland or Skye deserve more than an overnight. You are short changing them.

Looking at Shetland - what time is the flight from Edinburgh and what time will you get there? What time is your flight back the next day. How much time will you actually have on Shetland. NOTE the airport is at the southern tip of Shetland so will take a long time to get to anywhere else. What are your friends expectations? Is he wanting to visit the Croft House Museum to see what the house his grandfather was born in would have been like? He might also want to spend time in the Shetland Museum in Lerwick, which is excellent as it covers a lot of the social history. Does he know where his grandfather came from and is he wanting to go to see that area?

Being realistic you need to plan on at least two nights! To make effective use of time, you will also need to hire a car to get around Shetland.

I recently did a one day trip to Shetland (North Link ferry from Orkney and back on the ferry that evening to Aberdeen. It was the only way I could get there but it was a very rushed trip but having spent many holidays there in the past, this was a quick nostalgic trip). So yes it is possible to do Shetland BUT you will be missing so much. The scenery is amazing and the feel is so completley different to the rest of Scotland with its Norse heritage. It really does deserve a lot longer.

Is the Jacobite train a must? The Scots Rail train runs along exactly the same route. OK it isn't steam hauled but views from the windows are possibly better and its a lot cheaper.

Depending on your arrival time in Edinburgh, you might be able to connect directly to Shetland. We've done that twice. You'll be a zombie when you get there, but you save a day of travel. There's LOTS to see and do on Shetland. You could fly back directly to Inverness and rent a car there (and pay the one-way dropoff fee).

I wouldn't spend two full days in Inverness unless there's something specific you're trying to do. Culloden, Clava Cairns etc only takes a day.

Rather than making the round trip on the Jacobite, visit it in the morning while it's sitting in the Fort William station, then drive to Glenfinnan and watch the train pass over the Viaduct at 10:30am or so. Then drive on to Mallaig and get on the ferry to Skye.

You could do something like this, or scratch something to slow things down. Unless you plan on mountain bagging, you could not stop in Glencoe. The scenery is nice, but it's nice everywhere .

1. Arrive Edinburgh, proceed to Shetland - rent a car
   1. Shetland
   2. Shetland
   3. Fly to Inverness, rent car, visit Culloden, Clava, etc
   4. Inverness
   5. Inverness to Fort William, Loch Ness, Castle, maybe a hike like Steall Falls.
   6. Fort William to Glenfinnan to Mallaig to Skye 8 Full Day on Skye
   7. Another Skye
   8. Skye to Glencoe 11 Glencoe to Glasgow, drop car off 12 Glasgow 13 Edinburgh 14 Edinburgh, Fly home

I agree with the posters who feel 1 night in Shetland is not worthwhile. It's NOT that Shetland is not worthwhile! I LOVE Shetland but as Stuart says the weather conditions at Sumburgh can change on a dime and you'll have disruptions down the line of your itinerary. I was there for 11 nights in July. The day before I was to fly out the airport was socked in by fog and all flights in/out were grounded. Fortunately a wind came up that evening and blew the fog out but I have learned to allow extra time on either side of a trip to Shetland (or Orkney).

BTW, even with 11 nights and it being a 2nd trip there, I did not see everything I wanted to see.

Wow, I appreciate all the comment so much!! You're all wonderful, and every point makes so much sense. Will definitely make revisions based on your suggestions! Cheers!