Granite countertops should not be viewed as an investment, especially if you're going to be the only homeowner in the neighborhood who has them. They do not increase the value of your home.
However, in a slow market, they can be what makes your home standout. That translates to a quicker sale.
If that's confusing, you should speak with a real estate professional.
PML of Longmont, CO
Granite is just one 'hard surface' out there. Marble, soapstone, corian, wood, and even concrete are also being used as solid surfaces in kitchens (and bathrooms for some of those). Shop around and see what both works for you and is in your price range.