We used a dupont product for granite and marble on our master bath vanity. The sealer was easy to use and the cleaner has a built in protector, although we usually re-seal annually (or uh when I remember).
I used Rock Doctor and liked it a lot. Very easy to use and haven't had trouble at all. Find an inconspicuous spot and spray it to test. It isn't as scary as you think and it seems more like spraying on cleaner, letting it sit, and wiping it off.