I assume your traveling on a Delta guess pass. I am not a Delta employee, nor do I represent Delta in anyway. However, I do non-rev quite frequently and have heard some horror stories about non-rev on DL to European destinations both on this website and word of mouth. Delta and many other airlines flights are packed full going to Europe. I be very careful. Non-reving in the summer regardless of what airline is very challenging. If your using a DL pass, your boarding priority is going to below DL employees. So that means for example, if there only 15 seats open and there are 15 DL employees and their family members non-reving. Guess who gets those seats before you? Delta has quite a large number of employees non-reving so keep that in mind. My recommendation is to be flexible and do not be shocked if you get bumped. Also, allow yourself to have a few "cushion" days to/from your destination should you get bumped especially since your going for a wedding or need to get back to your hometown for work, etc. I always tell my guest pass travelers always be prepared for the unexpected and have plan B. I will not give my passes if they have to do "must" travel--wedding, funeral, job interview, or other deadline travel events. I tell those people to purchase a real ticket. I also would talk to the (DL?) employee who gave the passes to you and have them help you understand the pros/cons and your travel alternatives. Again..........I do no speak for DL. I also do not want to sound ugly about it. I am just a realistic person who has seen lots of non-rev pass travelers travel on the peak periods and end up stranded at airports for hours or days. Many of them are broke and cannot afford hotels, etc. I hope you enjoy your travel.