With 2 or 3 days to play with, I’d def consider a Gorms circuit as above. A good mix of terrain and a proper feeling of ‘journey’.
Trail conditions are generally pretty good at the moment.
When doing a Cairngorm loop, it’s not essential to go right down into Aviemore, as from a biking perspective, stopping in bothies or at Glenmore Lodge are both viable. Glenmore does B&B, has grub and a bar. What else could you need..? Allows you to plan to come out of Feshie, straight into Rothiemurchus and along the Jack Drake bothy trail to Morlich.
After Glenmore & Ryvoan, you have choices; as it’s the more rocky and techy route, I’d not go Lairig an Laoigh if carrying bothy/bivvy kit though. The lighter option (but further) is to go to Tomintoul and up Glen Avon instead, passing Loch Builg, Cullardoch and popping out near Braemar.