I was about 13 when I visited, so I think the things that stuck out to me the most were the little things. Like having to pay for tap water or to use the restroom.
Yeah - this, this, and this again.
When I had a friend come in from Paris over 10 years, we spent about 10 days wandering around Chicago/Chicago suburbs/playing games in the basement like it was no big deal that he was in America for the first time. His main comment was, "it's not so different - it's just a lot of little things that add up over time." Well, 10 years later, I went to Paris as part of a study abroad class for my college honors curriculum, and realized exactly what he meant. After the first day there, me and the guy I was rooming with looked at each other and agreed, "this place just doesn't feel foreign enough." Because in a way, every single place in the world functions essentially the same - people go to school, pick careers, go to work, get paid, buy housing, share hobbies, have families, etc. It's just how they go about it that varies. And by the end of our trip, we decided it was foreign enough.
And yeah, the pay-for-bathrooms thing is pretty ridiculous. Us Americans went there and argued that it was a basic humanitarian issue. To be fair, they did have some pretty classy bathrooms though. Also, if you're wandering the street and find a pay-stall, don't try to sneak a second person in when the door opens to let the first person out. The ones in Paris wash down after use. Another person from another group tried that and got soaked. By contrast, we also had to carry water bottles everywhere, since apparently the French don't believe in drinking fountains.