I find that people who enjoy the Chieftains also usually enjoy Bothy Band and Planxty. And anything with Liam O Flynn, Na Fili, Michael McGoldrick's "Morning Rory" is excellent. In the Matt Molloy/piping style, I'd also consider Seamus Egan too. Catherine McEvoy, or Joe Burke (I'm rather partial to Sligo style myself, but love Joe Burke). Certainly the early Maighread Ni Mhaoinaigh and Frankie Kennedy albums are wonderful too for the flute/piping/Molloy sort of personal style. "O Riada's Farewell." Seamus Ennis. Anything by Micheal O Suilleabhain. Willie Clancy and one of my favorite pipers, Ronan Browne. Leo Rowsome perhaps. I'd try to vary the regional styles a bit, but give him a taste of some different personal styles too.

There are really too many to mention, but I'd guess if the man enjoys the Chieftains, he would likely enjoy anything with pipes, harp, piano and harpsichord, and flute, as those instruments are the signature sound of the Chieftains.