I would agree that what is important is the group that is sponsoring the trip.

I believe that it is important for young people to experience what the world is like. And most of the world is poor. I took my son on a "mission experience" to Costa Rica when he was 12. At 14, he traveled to the Dominican Republic to work with Hatian refugees there. Seeing poverty can be a life changing experience for a young person (and for an older person, too). I have traveled to Nicaragua during the Contra era, out into the Atlantic coast region, to El Salvador, leading a Habitat work project in a small village. These have been transforming experiences for me.

She will experience culture shock, not there, but when she returns to the States and no one understands the experience she has had.

A daughter of one of my friends died in Argentina working on a mission project because the heater they were using vented carbon monoxide. And other children have died in the US in car accidents. Everything we do carries risks. We tend to under rate the risk of the things that are familiar to us (like driving a car) and over estimate the risk of the unfamiliar. Learn as much as you can about the organization. Trust your judgment. And if it is a part of your belief system, pray.