Switzerland vs. Rome clothing

Layer your clothing. You can easily travel from temp. zone to temp. zone with layers. There is no way to predict what the weather will be...rain, sun, snow. Take a light weight water proof jacket, a light fleece piece to layer under or use either on their own. Take a scarf for your neck or head to keep warmer.

Bathrooms in Italy. If you are in a larger city, you can use the bathrooms in McDonalds/Burger King, etc. Be prepared to purchase a small item, or pay.

In my experience in Italy, there aren't many public bathrooms, but you can use them at train stations (expect them to be a bit on the dirty side, or totally gross) Plan your day accordingly, when you eat lunch, or dinner, even in a small town, you can ask to use the facilities, or they will direct you to one.

The weather in Switzerland depends 1) on where you will be in Switzerland and 2) especially the elevation you'll be at. If you're at the Jungfraujoch or Shilthorn at 10,000+ feet, it will be radically colder than if you're at 1000 or 2000 feet elevation. So, we can't tell you what the weather in Switzerland without more information. We can't tell you anyway but at least we could give you averages, if we know more.

Maybe you're not going to Milan, but when I was there in November, I've never seen such dirty bathrooms! They were free to use, but they were so smelly and dirty, I was about to be sick! These were in fast food places. I would rather pay, and use a clean bathroom. I don't remember Rome having such dirty bathrooms.
Germany and Austria are cleaner countries. I'm sorry to say this because I am Italian, and am very proud of that, but I wish their bathrooms can be clean!
Liz gave some good advice on where to find better bathrooms in Italy.

If we were near a hotel, we were never turned away from using their facilities, but we always asked first.

Where in Switzerland? In the Alps it will be cold in May. In Rome it will be moderate in June....maybe even hot on some days. When it is cold you should always layer your clothing like Ellen suggested.

RESTROOMS
They will vary from one town to another. Generally they will be cleaner in Germany and Switzerland.

When I made my first trip to Europe in 1979 my uncle advised me never to pass a restroom because one might not find one until tomorrow.

That as true in those days. Today we use restrooms in the American fast food places like Ellen suggested. And we always buy something.

WEATHER
We take a poncho and a small 12 inch umbrella. When I want to predict weather I use yahoo.com weather page for average temps by month for any city.

In Italy--use the bathrooms at the sites you tour. Museums especially have nicer ones (the ones in the Uffizi are downright swanky). Restaurants and hotels are also good options. If you get desperate, duck into a bar and order an espresso. This saved my dad when we were in Lucca and I got to have a great cup of coffee! :-)

We didn't have trouble finding restrooms in Italy, just make sure you have some Euros with you! We have paid up to 1 Euro each.

Just a funny note, when we were in Germany we had to pay to use the restroom (which was normal everywhere) and my husband was asked if he was sitting or standing! Maybe the price varied depending on what he was planning to do!!

I think you have to be prepared for a wide range of weather at that time. Two years we were in Rome during the first week of June and I thought we would freeze to death. One night was so cold that the sidewalk cafes did not open. And we were unprepared because EVERYONE told us how hot Rome would be at that time. We returned the next year at the same time and had some long sleeve shirts, jacket and -- of course --- didn't need them.

PS -- Find good toilets in Europe is learned behavior. And as someone else posted, you never pass up an opportunity to use one.