An off road five dayer I wanted to do was starting at Achnashellach station, ride down to Coulags, dump stuff in bothy, ride without camping gear up and over to Annat, then back again via the Coulin pass and trail down the side of the river lair.
next day ride from the bothy down the hill, along the road for a while to the Attadale gardens, follow forest roads to Loch an Iasaich then descend the hill track to Glen Ling and follow the river out to Killilan, up the road a little then push up sometimes steep but good trail to the Falls of Glomach, then descend the Bealach na Sroine path to Glen Shiel.
Next day ride up Glen Lichd to Alltbeithe Hostel. Ditch stuff and go explore singletrack around Glen Affric, or even investigate paths up some of the nearby munros, there looks to be some good trails up there (Coire Leachavie anyone?).
Next day descend the trail through Bealach an Sgairne and ride back to Kyle of Lochalsh. This seems a bit of a cop out but I don't know any good riding between Glen Shiel and Kyle of Lochalsh. You could split up the riding above ^ in order to make this day five instead of day four.
Either way your enjoyment of the above would be dependent on your fitness, your sense of humour in the face of the occasional hike a bike, and how light you can pack your camping gear!