We recommend bringing one suitcase and one carry-on bag. If your trip includes an overnight train, bring as small a suitcase as possible; your luggage will be stored in the sleeping car with you and your friends!
Suggested packing list

Once we finalize your flights, we’ll give you a confirmation number. Within 24 hours of your departure, go to the airline’s website and use your confirmation number to check in, confirm your seating assignment, and make any special in-flight meal requests.

You should get to the airport at least 2½ hours before your departure time (this gives plenty of time for check-in, security, etc.).

Sometimes, due to airline partnerships, the airline printed on your ticket may not match the airline you actually fly with. It might, for example, say American Airlines (AA) on your ticket but you’ll fly in a British Airways (BA) plane on your connecting flight in Europe.

The Federal Aviation Administration is a great resource for up-to-date info, tips and news.
FAA website

ATM cards are your best bet for getting money abroad. It’s easy, and you get a good exchange rate. You’ll most likely pay a fee for each withdrawal (ask your bank), so try to limit your trips to the ATM. Credit cards are also good; they’re accepted at most (though not all) stores and restaurants.

Be sure to call your bank and/or credit card company to let them know you’ll be abroad. They sometimes cancel cards when they see unexpected overseas activity.

How much you'll spend depends on what you want to do. Will you be getting by on bread and water or will you be fine dining and buying souvenirs every day? If you fall somewhere in between, we recommend about $60-80 per day for spending money.

Generally, tipping is not quite as generous abroad as it is in the U.S., but it is becoming more common. Your tour director can give you advice on tipping in the city you're in. Also, at the end of your trip, don’t forget to tip your tour director $3-4 per day (and $1-2 per day for the bus driver).