If you're going via the A9, not a great road and often single carriageway, then Pitlochry, a lovely town with a salmon leap on an old HEP station is worth a visit. Aviemore too, very much a tourist town, is again worth stopping for.
The A96 on the other hand, although longer, gives you access to a many more settlements and their attractions. Aberdeen, only today described as a major world city, is the gateway, not only to the Highlands, but also to a number of picturesque towns and villages. Inverurie, Huntly, Keith and Elgin are charming little towns with lots of character. And if you're into scenery......................wow!