Word which describes the feeling of an event or concept?

I’m looking for the word that can fill this blank:

I went on this trip, not knowing that she was coming, and when I found out that she was, the ____ of the trip changed for me.

It should be the word which describes the set of feelings or overall perception of this trip. It’s like the set of characteristics that define the event or situation. I’ve already disposed of words like spirit, feeling, outlook, atmosphere/aura, and notion.

Something is nagging me that the word might be a plural … which word is this, exactly?

I'd say "the tone of the trip changed."

...the dimension(s) of this trip changed for me?

5: a level of existence or consciousness

Or perhaps impact:

: the force of impression of one thing on another : a significant or major effect
- the impact of science on our society

Perhaps the atmosphere of the vacation changed?

atmosphere: the pervading tone or mood of a place, situation, or work of art

I think it sounds a bit awkward in your example, because it's usually applied to physical locations, but I still think it's worth considering:

ambience: The special atmosphere or mood created by a particular environment

One more (pardon the alliteration, it's coincidental):

aura: the distinctive atmosphere or quality that seems to surround and be generated by a person, thing, or place

There's mood, too: The mood of the vacation changed.