Thanks, everybody!
Thanks so much, everybody, for all your recommendations! Since "The Hand of Fear" was suggested to me by several people, I watched that first. I'll comment about it in the "Hand of Fear" thread on this forum.
Since Llin said that Janet Fielding was funny, the next DVD I tried was "Castrovalva." This DVD rocks--you guys have all got to see it, if you haven't yet!!! The commentary is fun and interesting--absolutely no awkward silences. The extras are great, too--esp. interviews from _Blue Peter_ and _Swap Shop_.
My friend loaned me "Castrovalva" in a boxed set with "Logopolis" and "Keeper of Traken," so those are the next two DVD's that I'll watch. After that, it's back to the library for more Sarah stories. :)
Thanks again, everyone!