Here's some of the more obvious ones, going roughly south to north:
Meall an Fhudair + Beinn Damhain
Beinn Stacach + Creag Mhor
Creagan na Beinne + Shee of Ardtalnaig
Beinn Chuirn + Meall Odhar
Beinn Bheula + Beinn Lochain
Monamenach + Duchray Hill (from Glen Shee)
The Fara + Meall nan Eagan
Glas Bheinn + Beinn na Cloiche
Creach Bheinn + Fuar Bheinn + Beinn na Cille (very good round)
Garbh Bheinn + Beinn Bheag + Sgorr Mhic Eacharna (even better!)
Beinn an Oir + Beinn Shiantaidh + Beinn a' Chaolais (a classic)
Askival + Ainshval + Trollabhal (maybe the best of the lot)
Corryhabbie Hill + Cook's Cairn
Beinn Iaruinn + Leana Mhor
Sgurr an Utha + Glas-charn
Garbh-bheinn + Belig
Glamaig + Beinn Dearg Mhor
Beinn Damh + Beinn na h-Eaglaise
Beinn Enaiglair + Meall Doire Faid
Beinn Leoid + Meallan a' Chuail + Meall an Fheur Loch
Meall Horn + Sabhal Beag
I've done quite a few of these if you need any more specific route advice, and this might help you find some more:
https://www.hill-bagging.co.uk/fullmap.php?qu=C&ty=C,G&ct=EWMS