Some advice on renting and driving:
A reservation made from the USA is strongly recommended. Be sure to purchase the full collision insurance with no deductible, however, as small incidents with cars add up to big bills quickly in Europe, even for tiny cars.
Rent a small car. Your life will be much easier. You will be miserable with any kind of SUV and they will try to offer you those, especially in Switzerland. If you can't drive stick... learn to before you go.
Most city centers in Europe are now pedestrian with limited access allowed to cars for residents and hotel guests. Always enquire with the hotel what the parking arrangements are - particularly in Italy. Also beware of not getting trapped inside a city after a certain hour. The French in the south of France in particular love to install hydraulic gates that may go up after a certain hour.
Do not speed, ever. There are speed cameras everywhere in Europe and there is zero tolerance and huge fines. They will send you a bill and the rental car company will pay it "for you" along with a surcharge "handling fee".
When you are on the interstate, NEVER, EVER block the left lane or pull out into the left lane to pass a slower vehicle in front of a car that is coming up behind you. Ever. To do so is illegal and very dangerous. European drivers who are passing in the left lane are overtaking at a high rate of speed and they expect you to see them coming and stay put until they have gone by, and they do NOT slow down for a car in the left lane because they expect you to be out of their way by the time they reach you. Despite what I just said about speeding, you will encounter very fast cars and bikes blowing by you on the interstates in Germany, Austria, France, and Italy and just about everywhere else. I don't know how they get away with it but they are well in excess of 100mph and more like 120...140mph.
The ticket for blocking the left lane on the Autobahn in Germany is 1,200 Euro... don't block that lane.