My partner and I are confident travelers and we take several trips a year, but our careers thus far have kept those trips limited to domestic locations only, and on the shorter end of things (long weekends mostly). As we look ahead to branching out into Europe (a first for us both), I'm curious to gather any practical tips-and-tricks and odds-and-ends info that would specifically apply to European/international travel that an otherwise experienced traveler might not know to be aware of.
As an example: I remember learning that you provide your passport when you check into the hotel and quickly realizing it's a whole other ballgame than domestic travel. Whether it's about flights, immigration/customs, money, jet lag, etc, I'm all ears!
The first/other thread I started about packing bits-and-bobs was so wildly successful I thought I'd try for a second lightning strike :)