Has he seen Buffy, though? Seeing Giles (ASH) was much more of a kick for me than some OldWho slag I don’t know…
It’s easy enough to pick up the significance of an old companion I’d have thought. The existence of K-9 might be a little trickier to understand.
:mad:
Well, I want to be clear that I am not saying that School Reunion isn’t a great episode. 
Personally, I loved it. But we have very limited time, and for me a lot of the punch of that episode was in seeing old familiar companions reunited. Without that history, I think some of the other episodes are a better pick.
Actually, a few past companions had later run ins with the Doctor. Doctor #5 met up with the Brigadier in “Mawdryn’s Undead”, and with Doctor #7 in “Battlefield.” Then in the Five Doctors anniversary special Susan Foreman, the Brigadier and Sarah-Jane all met up with past incarnations before all meeting Doctor #5. And Doctor #6 met up with Jamie McCrimmon (as well as Doctor #2) in “the Two Doctors.”
Actually, Sarah-Jane’s reunion with the Doctor in the new series doesn’t seem to jibe with the Five Doctors special. In “School Reunion”, she acts as if she hasn’t seen the Doctor since their goodbye scene in “the Hand of Fear.” She even says at one point that she thought he might have died, given that he never came back to visit her - but she did meet him again.
Anyway, for my money, the best episodes to watch are:
Girl In the Fireplace
Impossible Planet / the Satan Pit
Human Nature / the Family of Blood
Blink
Silence In the Library / Forest of the Damned
Midnight
What, did it need a smiley? I was being cheeky.
I know - mine is faux-outrage.
Reconsider School Reunion, as it establishes Sarah Jane and the Doctor’s importance to each other. I showed it to a friend who had never heard of Sarah Jane before and she had no problem understanding it. But without that episode, Sarah Jane’s presence in The Stolen Earth/Journey’s End is sort of meaningless.
I’m not at all fond of the parallel-world episodes, but I don’t think the series 2 finale would make a bit of sense without them. Where did the Cybermen come from? Why is Pete alive? Where has Mickey been? So I showed my friend the Cybermen creation episodes, but I apologized first and promised her it would pay off later.
Blink and Human Nature/The Family of Blood were the best of series 3. The climax of the series finale still makes me cringe just thinking about it, but I thought John Simm’s performance made the whole thing worthwhile.
If you’re going to show someone the finale of series 4, you must show them Partners in Crime, Planet of the Ood and Turn Left, at a minimum. But Turn Left makes a lot more sense if you’ve seen the rest of the season first, so that’s a tough one. Maybe it would be better to hold off on the finale for now and watch Silence in the Library/Forest of the Dead, which is a standalone story but may not be in a few months.
The Time Lords of Gallifrey wiped everyone’s memories. Hey, why not?
To get the full impact of The Waters of Mars, you really should see The Fires of Pompeii, The Planet of the Ood, The Stolen Earth, and Journey’s End.
But you really shouldn’t watch The Stolen Earth until you’ve seen Turn Left.
And Turn Left has major callbacks to The Sontaran Strategem/The Poison Sky and Partners in Crime.
That leaves only The Doctor’s Daughter (which is a pretty lame episode) and Silence in the Library/Forests of the Dead (which are very good and which, come to think of it, foreshadow both Turn Left and Journey’s End.
Damn. Counter-whooshed. You reversed the polarity of the whooshium flux…
By far the best Doctor Who episode, hands down, without question is Doomsday.