The Mezzanine

I tend to think that the multi-episode arcs require too much knowledge of the ongoing plot. I'm picking stand-alone episodes, in the hopes that the new viewer won't be confused. :)

I can't remember the names of any of the episodes...

I believe you're talking about...

PK Girl - I think that's what it is called

PK Tech Girl.

The best ones in S1 are the one in which Chiana shows up,

Durka Returns.

and Crichton pretends to be a Peace-Keeper (it's when he starts wearing the leather), and the ones that follow it.

A Bug's Life, Nerve, and The Hidden Memory.

Where it appears they've made it back to Earth, but in reality it's just aliens studying their responses.

A Human Response.