Several Links are provided as points of reference. Virtually the entire trip was planned and arranged via the internet. Many hours went into planning it. The three of us kept in consistent contact e-mailing websites and other ideas pertaining to the trip. A Eurail pass is a must. Nothing beats the train system in Europe. It is flawless.
We all traveled very light. All of us brought disposable clothing. I returned with less tahn I came with and had plenty of room for souvenirs. There was no city which we visited where it was too hot. All of the cities were much cooler at night.
The people in every country were extremely friendly and helpful. Frankfurt was the most American city. Many people spoke English fluently. English was spoken throughout Paris, but our attempts at French were very appreciated and went a long way when we were looking for help, advice, or service. English was not a problem in Zermatt. Once again, our attempts at German were very appreciated. Trento is not really a known tourist destination, yet one can find help in English. Italian is needed in the area. It is still amazing that someone we just met on a train walked us from the train station to our hotel. That pretty much signifies the friendliness of Trento.
Picking a favorite city is a tough call. To feel as though you are in America, then pick Frankfurt. If it's hustle, bustle, and culture then there's no place like Paris. For complete relaxation and exceptional scenery, Zermatt. Trento would combine the scenery of Zermatt with the city life and art of Paris (on a smaller scale). I really can't include Covelo here since I'd be really partial to it!
Before traveling to Europe, learn either French, German, or Italian. It will make the trip more fun and will be appreciated by the locals - if at least for a good laugh at the attempt!