I would like to echo some of the other posters. Plan carefully.

Stirling is a nice, central location, but it'll still take a little while to drive to some of the more remote locations, etc. When we were in Ft. William we found that we missed something near Stirling. Took a couple (3?) hours to get there and a couple hours back.

Stirling Castle is definitely worth a visit, too. They were working on it when my wife and I were there in June, but it was still very much worth the visit.

I'm also with Jock, in that it's actually best to find a local area where there's a couple things you want to visit. Stay there for a day or two and see what you went to see. Then go to the next area for the next couple of days. It's nice to only have to drive for 45 minutes or so to get somewhere. As well as it's nice to not have far to get back to your hotel for rest...especially if you're hiking around the beautiful countryside. Takes it out of you. Add a couple of ales, and you'll really be ready for a nap. lol

When we went, we started in Edinburgh, then to Drymen (Loch Lomond Area), then to Kilmartin Glen, Ft. William, Skye, Inverness, and Glasgow for the return trip.

Of course, some morons rammed a truck into the Glasgow Airport a couple days before we were supposed to fly back, so we ended up flying out of Manchester instead. lol

Have fun on your trip, mate! Most amazing thing I've ever done short of getting married!