Hi, jnewmast,
I have to ask - when you say that you are visiting a place or sight, does that mean that you are going to drive by and have a look, or are you planning to get out of the car and walk/hike? The reason that I'm asking is that you appear to have packed a lot of travelling in to days three through six. You haven't given yourselves enough time to explore the areas you're visiting.
As others have pointed out, what looks like a short distance on your map usually turns out not to be. For instance, on day three you're going to pick up your hired car, which I'm assuming will be from the airport. The M90 only takes you as far as Perth. From there, you'll be on the A9, stopping in Pitlochry and at Blair Castle before heading on to Ballachulish via Spean Bridge and Fort William. Given a couple of hours each in Pitlochry and at Blair Castle, it would at the very least be early to mid-afternoon before you reach the A886 cutoff at Dalwhinnie to pick up the A86 for Spean Bridge. I can tell you from experience that the A86 is not a fast road!
By the time you have visited Fort William, it's going to be past supper time. You will still have the better part of an hour before you get to Ballachulish, and you're not going to have much daylight left to visit the Three Sisters Monument and Rannoch Moor.
On day four, if you are planning to drive from Ballachulish to Portree, give yourselves at least four hours. If you're stopping in Fort Augustus on the way to visit the canal locks, add an hour. Frankly, I would eliminate Urquhart Castle. You'd be adding an extra hour, at the very least, to your travels. You can see enough of Loch Ness between Fort Augustus and Invermoriston.
As Jacqui (Skyegirl) has pointed out, you have too much planned for Skye in the day and a half that you'll be there. Check out travel videos on YouTube, read some walk descriptions on the WalkHighlands website, and then pick out the walks which you find most appealing. The Old Man of Storr and the Quiraing are a little more challenging than the Fairy Glen or the Fairy Pools.. As Jacqui advised, Neist Point and Dunvegan Castle are way out on the Duirinish Peninsula, and deserve the better part of a day to themselves.
You've given yourselves time for a relatively leisurely drive to Oban, but do make sure to reserve a space on the ferry from Armadale to Mallaig. You may want to stop at some of the beaches along the A830 before you get to Glenfinnan.
You should check in to your lodging at Barcaldine Castle before driving on to Oban for a celebratory supper (if supper is not available at the castle), as Barcaldine is a bit north of Oban. There are several very good restaurants in Oban. As far as Oban goes, there is not a whole lot to see within the town. However, as you'll have one full day in Oban, you could take a day trip to Mull and Iona, visit Kilmartin Glen, or spend the day hiking on Kerrera.
I don't want to put a damper on your plans, but I can tell you from experience that it's best not to try to pack too much in to each day. I'd advise going back over your itinerary and narrowing down, or even eliminating, stops which are not absolutely necessary to your travel plans. Scotland is best savoured at a leisurely pace!
I can say, without a doubt, that you are going to absolutely love Scotland! There is no place in the world like it. (Even Australia!)
Best wishes for your holiday!
Mike (Auchterless)