Lisbon
I was never a big traveler until I met my wife; not that I didn't want to, but it just wasn't something our family did a lot of when I was growing up. Most "vacations" were centered around soccer tournaments around the country.
My mom always tried to get us some culture (usually visiting a Civil War site), but like most kids, I did not appreciate it at the time. I guess I could say the same for Spanish class.
During our European trip, I would say I enjoyed Lisbon the most. It was more laid back than Madrid and Barcelona, and getting a great steak at midnight at Café De São Bento was a bonus.