I spent a summer there as a college student years ago, it was a life changing experience! Most beautiful place ever!!!
I think depending on the age, and who will be with them. CR is pretty safe, I felt much safer there than when I lived in NY, and in Boston. Most crimes that happen there are petty thefts. DOes the teen speak any Spanish?
In the capitol city, there are a lot of pickpockets etc, but if the kids know to keep their money in a money belt, and nothing in their wallet and learn basic personal safety, I really think they should go if given the opportunity!
Let em go!!!!!!! If you are nervous, offer to go along! You will not regret it!