Good area for all these types of thing…
Gravel loops, there are loads of options that involve just riding around in the woods. Basically head toward Feshie bridge, upstream there’s loads of good stuff to explore between the minor road on the west of the river and Glen Tromie. Generally everything ends fairly quickly back at a minor road or nice track by either river (Tromie or Feshie) and you can use those to connect all the various bits together. Also the relatively new section of Speyside way here is accessible gravel tastic. North from feshiebridge on the E side of the river toward Loch an Eilean is the same, loads of stuff and mostly loops back to the road before you get too lost. Some of the tracks round Lochan Gamhna are pretty filthy for gravel biking though but nearly everythign else is good. From Loch an Eilean head NE through to Rothiemurcus and loch Morlich… basically as long or short as you want combining whichever of the above appeals.
Trail run – Uath lochan area and Feshiebridge area, just follow your nose type stuff
Fell Run
Sgorr Gaoith loop (park between the airfield and Auchlean, watch for Capercaillie in the woods lower down esp if an early start)
Round Coire Garblach onto Moine Mor, down from Carn Ban Mor (park before Auchlean)
From Loch Gynack up onto the hill (forget the name, start Kingussie, up the golf course road)
A’Chailleach (sp?) out and back from Newtonmore