The thing to remember is never to use the word espresso, coffee is caffe in Italian, and an espresso is un caffe.
Your Spanish cortado would be un caffe machiato and your wife would ask for un caffe latte, not sure about the americano but think it's the same.
This article might help you -

http://www.lifeinitaly.com/food/coffee.asp

xx lassi

Italian is not so difficult, you have just to know a few stuff.

for an americano you'd better ask "caffè lungo"

for a latte caffè latte