You chose one of the creepiest stories from Tom Baker's first season. Ian Marter (Harry) later became one of the authors who novelized some of the Classic Who stories for Target. "Ark in Space" was one he did - an excellent job, as he would have known more about it than any of the other Target authors. His skills at describing the creepier elements of this story were so... descriptive... that I nearly lost my supper (was reading it in the cafeteria at the local college, shortly before my evening anthropology class).
The first-season Baker stories had some really good scenes like this one, when the Doctor has philosophical moments. His best one, though, was in "Genesis of the Daleks" when he hesitates to kill the embryo Daleks. From his point of view, he's seen centuries of death and destruction due to that species, but from the Daleks' point of view, they don't (quite) exist yet. It's the classic conundrum of "do you kill a child who history says will grow up to commit genocide" if there's a bare chance to prevent that from happening.
I wouldn't call The Tripods an uplifting series. There are parts of the series that deviated quite a long way from the novels, so they didn't actually finish the whole trilogy (or at least if they did, the rest of it wasn't available in Canada). It was actually pretty grim in a lot of places, but if I had to pick an uplifting theme, I'd pick friendship and sacrifice for the good of one's people.
My own movie choices would be Contact (previously mentioned upthread) and Short Circuit ("Johnny 5 is alive!" "No disassemble, no disassemble!").
TV choices: Space Island One (about an international group of researchers living and working on a space station in orbit around Earth; there's an emphasis on science and some stories go into the ethics of doing research because of profit vs. because it's beneficial).
One of my favorite episodes of the series is when one of the female researchers gets pregnant and has her baby aboard the station - the first human born off-planet. The entire group helps her through labor and delivery (there are only 7 people up there), and it's rather poignant when the mother holds her newborn daughter and shows her through the viewport what Earth looks like.
Uplifting SF literature... hm. That's really subjective. There's only one short story I know of that is capable of satisfying both religious people and atheists, and that is "The Last Question" by Isaac Asimov.
