In reply to Percy2012:
I've done it over 2.5 days in November including all the summits of the Grey Corries, Aonachs, CMD and Ben Nevis. That wasn't a particularly fast pace, a determined walker could do it all in 2 days. And a runner could do it in a single day, though prob not all in daylight at that end of the year.
As I recall, we bothied in the Lairig Leacach at the end of our first half day from the train. Then camped on the Grey Corries/Aonachs col on the second night.
There's loads of scope for variations: the glen route perhaps, plus one or two of the Mamores in passing.