Congratulations!!! I can tell you as a grandpa to six beautiful grandsons, they're a LOT more fun than your own children.
One word of caution though, they will really wear you out, especially when they're young. We were out at a nice resturant with my son and his wife and two sons ages 5 and 3. Of course as I headed for the restroom to wash my hands, they wanted to go with grandpa. As they burst into the restroom there was an older gentleman washing his hands and he remarked, "Where do they get all their energy?" Right at that moment, I figured it out; they suck it all out of their grandparents!
Good luck and enjoy!
Jim Smith