I walked the South Loch Ness trail a few years ago. It was very pleasant and quite easy going, but as I remember there was a certain amount of road walking. The roads were pretty quiet though, and there was a pub or two along the route. The Falls of Foyer are certainly worth a look as you go past. We met a few people who were joining it to the east end of the Great Glen Way to make a Loch Ness circular.