Aha! That’ll do nicely. 
Yeah, a handful of arcs, not a handful of episodes, and the old Who shows were never exactly in a hurry to get to the conclusion.
IIRC, there’s at least one arc for each Doctor, and a few (Tom Baker, in particular, and Patrick Troughton, now that they’ve added the recently discovered lost serials from his run) have multiple arcs.
The Tomb of the Cybermen.
I’ve watched a handful of the classic episodes. The one I have liked the best so far is Spearhead from Space. It’s the first episode of the Third Doctor. I like regeneration stories, and it introduces the Autons and the Nestene Consciousness. It also has Brigadier Lethbridge-Stewart, who is a great character.
I’m currently watching The Three Doctors, which is pretty good so far. The bickering between Two and Three is hilarious.
Both episodes are on Netflix.