D.F.
Not in a million years would I have let my 17? year old daughter take off with 4 or 5 other kids who are 18. Now this is just my opinion.
What were you doing at her age?? I would not care if she was an honor student or not. Have you talked to the parents of who she will be visiting?? Have you ever had trust issues with any of these friends she may be going with?? Do you know them all??
Good Luck with this decision!