Street names in Rome and Florence

Not posted as visibly as here. Generally, you can find the street names written on marble plaques on the sides of the buildings nearest the intersection, not on sign poles like here.
Also, sometimes the street names will change after a block or two, even though it's physically the same street.
I would say the Italians are not as compulsive about posting street names, compared to North Americans and Germans. :)

I feel like it can be really hard. Especially to find restaurants out of a guide book. We usually just wander until we see something that looks good. Or get sent by the hotel to a recommended one. The large sights seem fairly easy even using a map from the TI. We now have an I phone and found in London the GPS worked very well. We are in Italy in May and hope the GPS helps.

"the street names will change after a block or two, even though it's physically the same street" - In general very few European towns or cities have "blocks". A street runs from one junction to the next. There will be 2, 3 or more other streets running from that junction in different directions, all with different names.
Street names in Italy (and many other European countries) are shown on the side of the buildings at the corner of the street, above head height. See example here: http://3.bp.blogspot.com/-Tz5mKOzC-vA/UaEJRg_D8RI/AAAAAAAACzw/1OFRkEb4daQ/s1600/Vicolo+del+Leonetto.jpg

I find Google maps is not well designed for European cities. I find www.openstreetmap.org clearer.

An example of streets changing names, in Rome the street that runs along each side of the river is the Lungotevere, with specific sections having different names following "Lungotevere".

Most of the time name changes occur at a major intersection.

Why do you need to look at the street names while you walk? Street signs are up above, if you walk and look up at the signs you might bump into a pole or step on dog poop. Just look straight and watch where you step.

Street names may be on a marble plaque on the building at the corner (see below). That is the most common in historical centers where you are likely to be:
http://www.ilsitodifirenze.it/sites/default/files/immagini_articoli/foto.PNG
But in some areas, generally in more modern neighborhoods outside the city center, you might see different types, like this type or something similar.
http://www.abitarearoma.net/photos/1105.jpg

For the big cities of Europe, I have found Goggle Maps to be quite useful and detailed.

On my first (driving) visit to Great Britain, I grumbled about their "inconvenient" street signs, posted high on the corners of buildings. Little did I know that those were the largest and boldest street signs in Europe. In Rome and Florence, you may find only one corner of an intersection marked with those classy marble signs, so check all corners. Navigating by landmark buildings will also help.

In a Rome metro station, look for a neighborhood map inside the station before exiting. Rome does have some nice, square streets, so that when you pop up out of the Metro, it can be take some effort to determine which direction you're facing. Some people carry a compass.