My friend wants to take his 21 year old daughter on a cruise for her graduation. She would like to do a river cruise or explore Europe...he would like to do a Mediterranean cruise and explore the southern countries. I know them both very well enough to know they'd both be happy with either. They can travel in late August. Are there specific lines or itineraries that might offer more for her age, but also offer something for him? I'm trying to help him navigate this- I've sailed the Mediterranean and traveled Europe- but don't know much about river cruises and worry that may not be as much fun for someone her age, but I'm sure I'm wrong :) Thanks!