I would forget the NC 500 if you are staying in FW. For the NC 500 you really need to be up at Inverness or Ullapool. West is best. Nearly all single trackers.
Dont know how much you have been up here on a bike so I would recommend from FW:
South...Kinlochleven loop (B863) then down to Connel (bridge/Falls of Lorra if you are lucky with the tide) onto Oban for food (A82
across to Dalmally (A85) to Tyndrum then back through Glencoe.
West... Out the A830 Glenfinnan ("that" bridge from "those" films) onto A861 head south to Ardnamurchan Lighthouse. Back via Strontian and the east side. Would love to recommend Mull, but I would want to be staying on the island.
North... Isle of Skye, Portree, Uig (The Fairy Glen/ Skye Brewery!!!) The Quiraing over to the east and down. Loop round to Plockton back on the mainland.
Applecross of course.Work your way back from Shieldag. I would recommend doing this loop on a separate day.
East... Cairngorms. Spean Bridge (Commando Memorial) then off the A86 at Kinguissie for the B970. Take a right at the end of this quiet gem and head up to the ski slopes. A full loop would be over to Tomintoul/Braemar/Spittal of Glenshee (I would say this part is a must) About 250 miles but good roads.
Hope that gives you some thoughts, 7 days is great. Better chance of getting some "good" ie dry weather. Some of these roads are as spectacular as I have ridden so dont worry about repeat rides on them, especially tackled from the opposite direction (feels completely new!)