Wasserfallen is at the end of the number 70 bus line (or for a shorter journey, train to Liestal then pick up number 70 bus from there) .. cable car up into the Jura hills, lots of restaurant and play park opportunities .. for those who fancy it, a 30 minute walk takes you to a lovely view point where, on a clear day, you get to see the Alps. Typical Swiss mountain restaurants .. and for the more adventurous, some really great hikes along the "crêtes" (cliff edges) in direction of Passwang. Oh and a few nice hikes that are buggy compatible.
Here is the link
http://www.wasserfallenbahn.ch/
We go often - with our young children, and can recommend the walk over to Waldweid Bergrestaurant .. from there you get the Alp views and there is a little play park and goats to pet etc.