Tayside Grayling fishing can be brilliant, with Tummel, Tay, Erict, Dean, Isla ans earn all offering the chance of sport. some other waters (Almond, Braan below the falls and Upper Garry) have them as well (Garry was stocked a few years ago apparently, but fish are, i'm told, few and far between. Pity as it's the closest one to me)
Trouble with all the above, especially the 'big two', is the weather. Well especially for fly anglers, that is, as these waters can get a wee bit 'big' in prime Grayling time. Tummel does have the advantage of the water being controlled somewhat by the dam, and can be a good 'fall back' if things turn dirty on the others, but i've always struggled to hit grayling on here, well with any regularity that is.
Not sure about the smaller streams as i've yet to add them to the fised list (apart from the Earn that is), but i know the Earn is most popular, probably because it's the most reliable?
I know it's daft to drive past all these, but if i do hit out for the Grayling i still tend to head back to my folks and take in the Teviot and Clyde. Every year (usually on the drive home) it's the same old, why do i not fish these waters, as i speed back up the A9. Don't know, except that as they can be 'unpredictable' certainly weather wise, often it's more a case of being able to pick the moment right, rather than wait until the weekend and see what happens for the best chance of sport, and you run a good risk of driving all that way simply to get 'blown out' by big dirty water. In reality though it's probably more to do with the big miles shoved in in the trout season getting the better over the wee break from all that and (more importantly) stocking up on the 'Brownie Point Bank' for next season that wins
Teviot and Clyde offer free 'digs' at the folks and retail therapy for Mrs L in Edinburgh
Anyway, what you want to do is seed the Don / Deveron system (especially the tribs) as the sport this would offer would be phenominal. You'd all be ok 'cause i'd definately get the blame for this anyway