To start check out www.hikesantaclarita.com for many trail details and maps.  Other local trail favorites include Towsley Canyon (off the 5 freeway) at the Calgrove exit which offers a 2 mile and a 5 mile trail with fantastic views and Placertia Cyn (off the 14 FWY) from the Nature Center (Canyon Trail) - FANTASIC!  Three steams to cross, mostly level, easy for the entire family.