Hi Slowpuffs,
I've not tried Milonga, so I can't help you with that.
My older son started and still loves Blue Note. Recently he has developed an appreciation for latakia blends. He seems to really like Frog Morton.
Here are a few aromatics that might suite your son:
pipes&cigars' Trout Stream
C&D's Autumn Evening
Dan Pipes Sweet Vanilla Honeydew
My guess is that he may prefer more traditional American aromatics and if so, Lane's 1-Q or the various Captain Black blends may be to his liking.
I will second Natch's recommendations for Pipeworks & Wilke's aromatics. I particularly liked Gotham Court and Rum Cake, especially because they seem to fit in with the Thanks Giving & Christmas seasons so well.
When the time comes for more of a "cross over" smoke (meaning less aromatic and more tobacco flavor) I would suggest McClelland's Honeydew and Pipeworks & Wilke's 191 for Virginia smokes and Pasha's Dream and Pembroke and Frog Morton for latakia blends.
Hope this helps a bit. That all being said, I smoke aromatics about 1/10th of the time.
TC