I dunno... I went from a Speyside to a Islay and loved it. I then moved to a Highland with no complaints... I like the smokey, peatiness of the Highlands, and I like the smokey, sea air taste of the Islays (I really like Bowmore, but am always searching for new stuff to try).

I would talk to your brother, and see what he is developing a preference for, and get him something from the same region, but a different distillery... just to keep relatively in line with his tastes, but help him keep an open mind. Whiskies are a lot of fun, and the nuances of a good malt rival that of the best Brandies (or in my particular tastes, Absinthe or a good beer) out there.