Is that an activity for your students?
I haven't traveled much, but here are my answers:
1) Italy. Especially Rome and Florence. I was 17 and it was a school trip. The best vacation ever!!!!!!!!!!!! I would repeat it right away... I loved every place we visited in Italy, but Rome and Florence were the ones I enjoyed most. First we went to Rome. I have always been attracted to ancient culture, so I loved the monuments, the Roman forum, the amphitheatre and so on. Maybe that's why I love Tarragona so much, because of its ancient Roman monuments... Anyway, I loved Florence because , in spite of my youth, I kept thinking that was the craddle of Renaissence. Michael Angelo, Da Vinci, Boticelli, Raphael... That was a paradise.
2) England, Scotland and Ireland. Why? Because I've got a degree on English Philology and yet I have never been there!!
The only English-speaking country I've ever been to were the US. It's time to visit the UK and Ireland now...