In Europe I missed big glasses of water with ice at restaurants! My family all just gets tap water at restaurants (because we that's what we like to drink). In London, when we ordered water they brought a small carafe (no ice) and 4 tiny glasses. At least it was free. In Switzerland they brought the tiny carafe and tiny glasses, but it cost $5! Which is is funny because on the streets in Switzerland there are fountains with free spring water that you can fill up bottle after bottle. We went to the Hard Rock Cafe for one meal and they had full size water glasses filled with ice (and straws!) and it was heaven.
Believe it or not, I missed the standard American bathroom stalls with the short door! Someone else mentioned that bathrooms were almost always downstairs in a random, dark place (which I found true as well) and then couple that with a hot, boxed in, usually very small stall and I felt claustrophobic! And also slightly scared I would be attacked down there and no one would know. Weird, I know!
I also missed air conditioning.