As our original plans to visit relatives in the US before departing for Europe fell through, I thought it would be nice to have my parents here for the Christmas season. Originally, we had only planned to take them to Paris for a few days around Christmas, but then there was also a pressing matter with my residence approval.
The approval had not come through yet when I left San Francisco, meaning the date on my passport stamp upon entering Luxembourg came before the approval. When declaring my arrival for my residence card, the date of entry into Luxembourg had to come after the approval. I realize that is convoluted and confusing, so suffice it to say I had to leave and re-enter the Schengen Area after my approval came through. This meant we had the fortunate bonus of adding London to our trip, as the UK is not a part of the Schengen Area.
NOTE: This was my first time visiting these countries (as was also the case with my partner and parents), so much of the experience includes tour buses and obvious tourist destinations. Despite what the snobs may think, I found it an entirely acceptable way to experience a city for the first time.