I agree with others that I think the parents wishes are what matters most, just be available if things change or their wishes alter. A couple of things I have done to show interest and pleasure at this new babies arrival are these. The day the baby arrives go out and buy 2 local papers and 2 main newspapers.. Then I take one of each and seal them up carefully and put them away, and look after them and then when the child reaches 18 , they can provide a little fun and quite a lot of interest at a party. In 18 years time it is not the headlines that are so interesting but often pictures and adverts for shops long gone, or what people wore which of course was unremarquable at the time , but get people remembering the fashion , and what they used to wear at the time. Landmarks that may have gone , and if the guests live in that locality now , they are keen to see what it used to look like. So I knew someone whose baby was born on the day the first man reached the moon. Then give the parents one of each when you get to see your grandchild, and say you got them especially to remember the day. Then I probably have grow a small woods worth of trees. The woodland trust plant trees in various places in the country. You dont have plaques and things but they will give you a map reference . So I have got trees for all types of family occasions, good and bad and our family have over the years been able to have a few walks together to see "our" trees. So the birth of your grandchild is marked in an ecological way and maybe in years to come you will be able to visit "their" tree with them. Overall I have celebrated my parents ruby , and then golden wedding, weddings of special friends, the sad death of my sons baby at 3 days and the meeting for the first time of a cousin from a long way away. My view is that as a family we have taken from the world during our lives and the tree planting marks out our life events and at the same time gives a bit back to the world. Even if at the time the parents dont appear to be particulary pleased , it does show your thoughts and care for your new grandchild, without forcing any action or directing of the parents and hopefully they will come to see them as rather special thoughtful ideas.