Another key effect that is used in many different types of music is chorus. Chorus takes the main signal and changes the pitch up or down to create a fuller, shimmery sound, kind of like playing a single note versus a whole chord. You could create multiple tracks with different pitches, but chorus effects are built to properly mix the sounds so nothing sounds off key.
Chances are that any of those shimmery guitar songs you have heard had some chorus in there. This effect tied with some reverb and a flanger produces that classic guitar vibe.
Here are two little bits of guitar I recorded. I added plate reverb to both, but the first has no chorus. Try to see if you can tell the difference.
Here is the same track with reverb, only some chorus was added to make it complete.