In reply to tistimetogo:
I'd disagree with others - I think the Lairig Ghru is really impressive, for the sense of scale and the feeling that you're on a journey through the hills that people have been walking for millennia. Also the views west into Braeriach corries. To me it feels really special and not like just any other hill pass.
I think LG is best walked north-south for full effect but I don't suppose there's much in it either way.
The Allt Clach nan Taillear path is vague in the upper reaches, and finding it in mist could take a bit of effort. Pretty clear lower down. It's steep but not silly.
But... Looks like you're planning to go up Macdui carrying your overnight stuff. In this case you'll have done most of the hard work by the time you're at the top. From the summit an alternative to dropping down the Taillear path, if you have daylight and energy spare, could be to head north over the plateau. That'll give you a more satisfying traverse of Macdui than a backtracky route. Have a high camp on the shoulder west of Coire an Lochain or around the top of Luchers if weather permits (good for an anti-midge breeze maybe), or if it's too windy up high then continue north to lower ground west of the Chalamain Gap to camp. Day 2 could then be the full LG north-south back to Braemar.
Or do you have to finish in Aviemore for logistical reasons?