"It Depends."

  If I was face to face with God and he told me to do something, there is no way I could defy Him.  
I am the type to obey every authority, so why wouldn't I obey God?  There are many who defy the wishes of human authority figures, so it should not amaze me that they would ignore the wishes of God.
  "OH! If we were going to Africa, I would totally be going on this mission trip!"  That statement may not seem harmful, but it is disrespecting not just those in Romania by saying 'they are not good enough for me to come to them' but also disrespecting those students and adults who are going on the Romania trip and God. 
  God knows much better than us humans, so if God leads us somewhere, we must follow; even if it is through a high school mission trip, where it may not seem of value.  But, in partaking in this mission trip, each of the forty individuals, student and adults, are carrying out God's mission; through this mission trip we are stepping out in the front lines, even as teenagers, something many adults have never done.

"Wherever you are -- be all there." 

It should not matter where a mission trip takes place, a true Christian should WANT to go wherever the opportunity is; God has given the opportunity for a reason, and if one uses the opportunity, God will allow great things to happen.  Sadly, many United States Christians are not truly Christians; the type who say one thing and do another, the ones who give us a bad name; the type who do not care about saving the lost from a life without God, a life of eternal dying, an eternal destiny cannot be changed, ever.