This may seems silly but it can really mean a day of fun! I've taken my kids on the train quite a few times and it has been an adventure every time!
Evie and I took the train from my in laws on Long Island to upstate New York via Penn Station which was so much fun! Walking around and looking at everything, having pizza for lunch, it was all an adventure!
Closer to home we have 2 trains at our disposal that can take us so many places! Pick a train (VTA or Caltrain) and pick a destination! Bring your own snacks and lunch or have lunch or a picnic at your stop!
Not only is the ride on the train and looking out the window fun (especially on the double deckers on Caltrain) but finding a new adventure at your stop can be just as fun! It really is a fun idea to do with your kids, they'll love it, I know mine do!