You clicked here thinking I was going to tell you about fun places to go, right? -- instead I'm going to give you suggestions for minimizing the chances of Bad Things Happening while you're off having fun. (Posting this in Parents Forum in hopes you will pass it on to your wonderful CC young people).
Cancun, Cozumel, Ibiza, the Bahamas, Mykonos, Phuket, etc. are fun beach destinations. They are also in foreign countries (passport required), and you must abide by the laws of those countries. If you get in a legal jam (drugs, for example) the U.S. Embassy or your parents can not spring you from jail. Jails in many countries house incarcerated Americans who have done a stupid thing while on vacation.
Leave detailed instructions of how you can be reached while on your trip. Check your e-mail, send messages and phone home periodically just to let folks know you're okay. That may sound self-evident, but you'll be surprised at how you'll get caught up in adventures and forget. You don't want your parents frantically tracking you down through US Embassies or the Marshals Service.
Photocopy your passport, ID cards, credit cards, plane ticket and Eurailpass. Leave copies with your parents, and keep separate copies in your stuff that you carry with you -- but separate from the originals. For instance, keep the originals in a money belt or passport holder (inside your shirt and concealed), keep copies in a zipped pocket of backpack or cargo pants. If your original documents get swiped, it is much quicker and easier to make an emergency passport if you have a copy. If copy is waylaid, your parents can fax it to you or the nearest U.S. consulate. (and you will get great respect at the local Embassy/Consulate for being such a sophisticated traveler).
Never leave your wallet, passport, or any valuables in hotel or youth hostel rooms outside of the safe. Youth hostels sometimes are prone to "inside jobs". Even if you lock your room, the desk has keys. Girls, try not to stay in youth hostels on your own, and if you travel with several friends, you should try to not split up.
Obviously, some of you are going to party. Take turns being a 'designated non-drinker'. One of the group should stay sober to watch out for everyone else and their stuff. Very important at rave parties, clubs, bars, pubs, or anywhere. Do NOT take open drinks from anyone. Do NOT do any kind of drugs (see above). Make sure you all leave together.
Check the websites of the embassies in the countries where you will be traveling for any advisories. Some countries have special requirements for immunizations, currency, or visas. Do this well in advance. Don't skip the shots and please DO the malaria prophylaxis if it's recommended for your destination (even if you're only going for a short time).
Try to get some of the local currency before you leave. Sometimes currency-exchange booths at airports can be a big rip-off. You can use your bank debit card in many countries, and people still use traveler's checks. Again, keep all money-related items close to your skin.
No matter how much of the local language you may know (and you should try to learn a few phrases), and even if you dress head-to-toe in the local garb, you are not going to disguise the fact that you're American. That's a strength, but also a responsibility. Remember that in some countries there are strong negative feelings about Americans. You can open up some minds with your good behavior, consideration, patience, and interest in the local culture.
A lot of my suggestions above may sound like a drag and time-consuming, but for people that travel a lot, safety measure become routine (securing valuables, looking out for each other).
Have fun! Learn a lot! Happy Trails, Bon Voyage, Buena Suerte, Buon Viaggio, Gute Reise, etc. etc.
P.S. I could tell you some stories...