I get those moments all the time, mostly little things, some of them mentioned above. Like the other day when I investigated Dragonsreach and checked out the balcony in the jarl's bedroom. Oh. My. God. The view! Seriously, if I could I would marry Balgruuf on the spot just to have that view!

Another moment was the first time I started a new character and went through the intro again, and suddenly saw and heard so many things I totally missed when I made my first character.

Turned a corner in the road and was astounded to see a khaljit merchant swimming through the air about 12ft above me.
Found one of my mannequins floating above the enchanting table in Honeyside. It was quite creepy actually.
Climbed a tower to admire the view and watched a mammoth fall out of the sky.

Strange gravity in Skyrim...

Realizing the voice actor for Garret from the Thief series is EVERYWHERE.
And that Cynic Endell is a send up to the character.