Hello Steve,
While your question is about gear, I think that the overall fun in the trip depends on several things.
My highlight has always been the driving portion of my trips. I love driving a car in other countries. Eating bread and pasteries in Germany and Austria is my second most favorite part of the trip. Lina and Dana quickly learned that "Itallian ice cream is the best" and that "fresh fruit juice is best in Germany" .... etc. Now they are back to Macaroni and Cheese and chicken strips.
I love experiencing other cultures. Taking photos is also enjoyable, but it is not the photo taking that I find the most interesting.
I was very happy with the M6 and the 35/1.4 Summilux for general photography since it allowed me lots of flexibility for using ISO 100 film throughout the trip. In dark churches, I used shutter speed 1/15, and I count on the negative film to be forgiving. The CV 25/4 is a gem for travel. Its slow speed is OK for street photography with ISO100 film. The 35/1.4 and 25/4 made a very good pair of lenses for the entire trip. Keep things simple, but have a back-up. I took along the EP-2, but I changed the camera bag one day before the trip, and I forgot in a side pocket the battery charger. I am glad that I still had my two film cameras (M6 and Bessa T) with me. I have no regrets about my choice of gear or film (Kodak 100UC). I did not use the XP2 since life was so colorful there.
I nearly took along a MF camera, but I left it home. I may (or may not) take a MF camera with me next time. Keep things simple and light.
I got in the end a Ford Mondeo with Turbo Diesel as a rental car. It had sensors for the front and for the back, which made parking more manageable in the narrow roads in northern Italy. Diesel costs around $7/gallon in Europe. Gas costs a little more than that. It took me a day to familiarize myself again with a stick shift car. Man, what a pleasure it was to drive on the Autobahn again and in the mountains of Italy.
The weather was great overall. We returned to a hot and steamy Pensacola! No sitting outside a coffeeshop for a Cappuccino is possible here, unless you enjoy sweating a lot. Europe is great for relaxing in the streets at some coffeeshop in the street somewhere.
The trip was great. Lina and Dana experienced briefly life in Germany, Switzerland, Austria, and Italy. They want to go back there "in two years." They are giving us a break, to save money for the trip!