Most people will recall that Lassie was appointment television for the whole family, usually on Sunday nights, as memory serves.
Having also gone by the titles, Jeff's Collie & Timmy & Lassie, the series spent 19 seasons, all on CBS, before being cut loose in 1973. Currently, classic repeats from the early years have been running on Retro as part of their Saturday morning package (check local listings), with a full hour each week.
From a Lassie fan channel comes the episode, "Sale of Lassie", with Jan Clayton as Jeff's mom.
June Lockhart, of course, would go on to star in Lost in Space during the mid-60's. In later years, the cast would also include Jed Allan (Days of Our Lives) and Pamelyn Ferdin (Curiosity Shop), among others. A revival was attempted in the late 80's, but didn't quite take. Nothing, in this case, beats the original.