Public Transit Recommendations - Edinburgh-Inverness

Consider the Friends Fare for that route. Savings would be considerate, but like the Advanced fare, non refundable and limited to that train and time.
Scenery is better on the train.
Ember are very comfortable and efficient with price and time on the road comparable. They offer ability to all sit together, great wifi (when there is any to be had) and a quiet ride. Your family may need to determine whether a toilet is a must. Though the buses are supposed to have them they are for emergencies and mau be labeled as 'out of order'.

first, and usual, question. Where has your limited train information been sourced? Have you used the NationalRail or Scotrail websites?

The rest comes later........

I also explored the Ember bus, but it appears there may be reliability issues.

Who is saying that, because it isn't true? The benefit of Ember bus is that the fares are non dynamic, so are always the same and can be purchased until 10 minutes before departure. They are also more frequent than the train.
This isn't a Rick Steves tour bus, in the UK all bus toilets are meant to be used, there is no rule about being for emergency use. That is a unique rule on RS- any bus tour from a UK based company doesn't have such a strange rule.
Scottish Citylink and Flixbus also run on the Edinburgh to Inverness route- Flixbus are dynamic fares, and Citylink are higher than Ember (although a bit cheaper if you book with Megabus, their code share partners).

The Advance Fares are not only on the 0838 direct train, but on other direct trains at 1332, 1633 (LNER) and 1733

But the 0632, 1134, and 1806 (all change Stirling), 1236 and 1441 (both change Perth) also have Advance Fares.

If the booked train is cancelled, then your ticket is automatically valid on the next service, although clearly seat reservations are not carried over- shouldn't be a problem in October.

Appreciate the responses!

first, and usual, question. Where has your limited train information been sourced? Have you used the NationalRail or Scotrail websites?

I'm using the Scotrail website, and also had a look on the NationalRail site.

Consider the Friends Fare for that route. Savings would be considerate, but like the Advanced fare, non refundable and limited to that train and time.
Scenery is better on the train.
Will look into the Friends Fare; not sure how to access this?

I also explored the Ember bus, but it appears there may be reliability issues.
Who is saying that, because it isn't true? The benefit of Ember bus is that the fares are non dynamic, so are always the same and can be purchased until 10 minutes before departure. They are also more frequent than the train.

I based that on a quick scan of TripAdvisor reviews -- while most were very positive, others complained about considerable delays when taking Ember bus. Glad to hear it isn't true.

With that said, we'd prefer to take the train rather than a bus; we have limited options for train travel where we live, so it's a bit of a novelty for us.

The Advance Fares are not only on the 0838 direct train, but on other direct trains at 1332, 1633 (LNER) and 1733
But the 0632, 1134, and 1806 (all change Stirling), 1236 and 1441 (both change Perth) also have Advance Fares.

Ok, this is where I'm getting into a muddle -- I only see an Advance Fare for the 0838 direct train on the ScotRail. (EDIT: I tried adding a link to my results, but it didn't work.)
Perhaps Advance Fares for the other trains are sold out? Or perhaps I need to go on the NationalRail site instead?

If the booked train is cancelled, then your ticket is automatically valid on the next service, although clearly seat reservations are not carried over- shouldn't be a problem in October.
Excellent, thank you.

The Friends Fare is the reduced fare afforded by buying the Family and Friends Railcard- https://www.familyandfriends-railcard.co.uk/

but that is no use, as there is no child travelling with you.

The alternative is 2x Two Together Railcards at £35 each, to get 34% off. But travelling on Advance or split fares you will be unlikely to reach the £105 spend on each railcard to make it worthwhile, and have an 0930 time restriction on weekdays- https://www.twotogether-railcard.co.uk/

The Scotrail website/app have been a mess since being revised last month (the app has a rating of about 1.4 on the app store, up from the initial 1.1).
The way they show fares is terrible- eg on the 1135 on 7 October the headline fare is £26.80 split tickets, you have to click the 'show fares' button to see that there is an Advance fare of £29.40 and 2 different Anytime Day Singles of £59.20 and £75.40, then click another button 'Show Restrictions' to see why.

The first is valid 'via Aviemore' (your route), the second via 'Any Reasonable route'- which means either via Aviemore or via Aberdeen.

If booking the return journey for 10 October you have to click on the 'add return journey' box.

If you do that then do the above steps again you will find with some effort that there is a fully flexible use any train Off Peak or Anytime Return (exactly the same thing) for £69.20 on the via Aviemore route.
Now £69.20 for a fully flexible use any train fare is not much more than 2x £29.40 (or 2x £26.80) Advance/Split fares where you have to be on the specified train.

The higher £84.50 is the any reasonable Route (via Aberdeen) fare.

Also on the full fare ticket you can break your journey anywhere on both legs-so say at Pitlochry heading north, and at Stirling heading south (as examples).
That return (not a single) ticket is valid for 5 days outward, and one month as a return.

So for instance if you break outward at Pitlochry that could be for 2 or 3 days before restarting north, likewise on the way back south.
That 5 day flexibility outward only applies on the Anytime fare, not the identically priced Off Peak Fare.

isn31c -- I followed your clear explanation and was able to book our train tickets. Thank you!

The ScotRail website is absolutely maddening. I planned our trip using the National Rail site and it was much clearer, then purchased at the end from ScotRail. Had a moment where ScotRail's site insisted we were trying to add bike storage (which wasn't available, and we hadn't this selected anyway), but that went away when I backed out and then went forward again. Success!