Scotch is expensive, so doing some research before buying is often times well worth it. Your taste might not agree with their's totally, but having someone who has tried hundreds of scotches might point you in the right direction. Their descriptions can also be helpful for you to find out what types you like as well. If you like peaty scotches you can look for scotches that have those for the tasting notes. If you like Laphroaig 10 year try the 15 year for something new.
I have enjoyed books from Michael Jackson and Jim Murray, but everything is going to the web so I have look for a ratings site for a while. Recently I ran across Malt Maniac's website. Every year they do awards for the year based upon their ratings, which include separate ratings for everyday malts and more premium malts. Check out the ratings for 2009 here.
A few Islay selection here I would like highlight that are more affordable, as in under $100 and are in the silver rating, since the gold ones are simply too expensive. Lagavulin 16 year took home a silver with a rating of 86 and is simply as good as scotch comes in my book. The Lagavulin Distiller's Edition comes in slightly higher at 88 and is a good change of pace. Caol Ila 16 gets an 86 as well. Bruichladdich's mega-peated whisky Octomore comes in at 85 although will cost slight more than $100. Laphroaig 10 comes in at 85, making it probably the best value in the silver. Ardbeg Corryvreckan also gets an 88, but will also cost more than $100.