4x06 Once Bitten
[Watch it (again) on Demand 5.]
13x02 Terror of the Zygons Part Two [2nd watch]
Damn fine story, this. Weirdly, I'm certain I've seen it before, but whole swathes are unfamiliar. Like the silly bit where Sarah Jane and some soldiers need to split up while chasing a potentially dangerous fellow... so Sarah Jane goes one way and the three armed men the other. But, y'know, other than that.
2x08 The One with the List [4th or so watch]
2x09 The One with Phoebe's Dad [4th or so watch]
I think I've quite consistently seen all of Friends' first season, but I've definitely seen some of season two (and, probably, later years) more than others. For instance, I'm very familiar with The One with Phoebe's Dad (which is also The One Where Gunther Has His First Line!), but in a few episodes' time it's The One with the Lesbian Wedding, which I feel like I've only seen a couple of times (I've seen the entire series through at least twice already, so, hey).
This doesn't signify anything, just something I've been mulling over.
2x04 Unintended Consequences
Every episode, it strikes me how clunky (and therefore painfully predictable) Sorkin's writing can actually be (see also: last time). On the bright side, at least some of the plot lines rattle along to revelations, rather than dragging every mystery out only to pay them all off at once in the finale.