http://www.royalmilewhiskies.com/default.asp
I'd agree with the other posters, the islay ones (ardbeg! cracking) are great but not everyone gets on with them, and the fact that your dad has glenfiddich makes me think that a highland or speyside would be a better bet
have a look at the map thingy on the royal mile to give you some ideas, although I agree with buzz and inbred, Highland park is very drinkable

