And while the number of Americans visiting places like Croatia is still relatively small —154,000 in 2006 compared to more than 2 million to Italy — growth is strong, up from 115,289 Americans who visited in 2005 and more than 200,000 expected in 2007, according to the Croatian National Tourist Office. AAA's bookings to Croatia increased an astounding 440 percent this year over last.

"It's the alternative Riviera," Frank explained. "Unspoiled. Beautiful. Great beaches, great food."

What will be the next Croatia? Van Tiggelen picked Montenegro, also known for beaches and good food. Frommer said the recent James Bond movie "Casino Royale," which was set in Montenegro, helped pique American curiosity about the place.

But her prediction for "the next Croatia" is Bulgaria. "It's right on the cusp of being discovered," she said.

ART: "Europe is not only one big museum, it also has a contemporary side, and this is a big year for contemporary art in Europe," Van Tiggelen said. Dokumenta, a major contemporary art event held every five years, runs June 16-Sept. 23 in Kassel, Germany.

TRAINS: A new high-speed train line that runs northeast from Paris begins commercial service June 10 to Champagne-Ardenne, Lorraine and Alsace; Luxembourg; Munich and Frankfort, Germany, and the Swiss cities of Basel and Zurich.