Lochnagar from Glen Clova. 5 munros, big country riding, Glas Alt descent - great day out. Duir is bang on the money about the eastern part of Scotland.
Dreish and Mayar - shorter day but two peaks with the Kilbo Path to finish.
Aboyne and Ballater - see the guys in Cycle Highlands for great route ideas.
Aviemore - soooo much to chose from. Cairngorm and Ben Macdui returning via Lairig an Laoigh. You can sneak in Bynack Mor on the return leg.
Anything round Rothiemurchus, Feshie and Inchriach are great. Bothy Bikes are the go to guys to speak to for route advice.
The Enduro trails as they now seem to be known in Kinlochleven are really rather good. Join them up with the likes of Binnean Mor or Stob Coire a Chairn for over 3000 feet of almost continuous descending.
I reckon Stob Ban would be great having carried up the Glen on a loop from Kinlochleven.
The Ciaran Path loop via Stanaig Bothy is a bit of a classic on a hot summers day.
Torridon is good but to be honest, I reckon there is better riding elsewhere. The scenery is stunning on the right day but once you've ridden the big loop, the choices then become a bit limited if you're not into your hike a bike backcountry epics. Definitely go but I would build it into your road trip. Check out Coastkid's blog for some Applecross ideas.
Finally, Pitlochry and Dunkeld has some terrific xc riding on offer. Escape Route will keep you right.
This barely scratches the surface. My taste leans towards big mountains, tech riding and big sky views. If that floats your boat, feel free to e mail me for more ideas.
PS FOG. The Aviemore Bunkhouse is really good for cheap and cheerful accommodation. Clean. Quiet. Right next to the Old Bridge Inn.