The Spring Canyon Trail is a short, fairly easy hike in the Newbury Park/Thousand Oaks section of the Los Robles Trail system that is great family fun.
This 1 mile trail runs west from the vicinity of Lynn Oaks Park, 359 Capitan Street, Newbury Park as well as at the eastern terminus of Hemlock Lane, at Heavenly Valley Road in Newbury Park (in the Ventu Park community) to a juncture where you can either continue straight ahead for about a half a mile towards the Los Robles Trail access point at South Moorpark Road and Greenmeadow Avenue in Thousand Oaks or veer up "Space Mountain" on the right. (The views at the top of Space Mountain are awesome but this is a bit of a climb and it is very popular with mountain bikers...probably not the best direction with little ones).
Out and back you can make this a 2 to 3 mile moderate hike or more if you add in the Oak Creek Canyon Loop or Los Robles Nature Walk.
You can also park your car at the Moorpark Road/Greenmeadow trailhead and make your way west towards the Spring Canyon Trail and perhaps eat lunch or snack at Lynn Oaks Park (which by the way also has a nice playground area, basketball court and more...but no restroom however).