Hey Grandad,
Congratulations and welcome to the club! I can testify twice over that it is a fun, life-changing experience, at least once they get past the nappy and being sick stages, and are communicating. It is the ideal chance for revenge upon one's own children. One of the standard behaviours in this respect is the doting grandparent taking grandchild out for the afternoon and returning said child to loving parent after an afternoon of fun and frivolity, bouncing off the ceiling like a helium balloon high on e-numbers and additives. And the child is too. I can highly recommmend blue smarties for this exercise in irresponsibility.
Grand-daughters are good too, because you can buy lots of things to "keep at home for when they come round", on the pretext that they haven't got them at home. Our two enjoy items such as the Brio train set, Scaletrix, remote controlled cars and a helicopter, and of course the MGA, the last being "Grandad's racing car", which they have worked out is unique and cool to be seen in by their other little mates.
Have fun,
MG Mark