[billybob123]

Estonia is great. Cheap, easy to get to and around, and if you're into a party scene, Tallinn is as hot as it gets. Women are beautiful (guys, not so much) , and everyone is looking for for a good time. Old town Tallinn in great for architecture and history. Parnu is two hours away and has a fantastic beach and spas everywhere.

Plus booze is crazy cheap.

I second Berlin as well. Vibrant city with a ton of history.

As for connections, it depends on the airport where you connect. You might have to collect your luggage and clear customs and immigration, then recheck it. Don't stress about it, it's pretty easy. Pick airlines wisely within Europe. Often the fares are cheap but luggage might cost significant coin to check. If you're connecting onto an international flight the luggage allowance is usually heavier, 22 kg or so.

Europe is a great place for an unmarried 21 year old without kids. Have a great time! You can't really go wrong with whatever city you go.

ETA: If you're leaving from Ottawa, consider flights from Ogdensburg, Cape Air flies to Boston, and connect to ant airline from there - tons of cheaper options to Europe that way.