In Rome...I think 2 full days is enough to see everything. They have bus lines (you'll see them, they are yellow, red, and green). You can get a 2 day pass on any of these for what I recall being around 8 to 10 dollars...and they only stop at the major sites. Passes are cheap, and it keeps you from walking all around and the buses come by often. For the tourist attractions, they have passes you can pre-order online (they also bypass all the long lines), but be careful of your arrival day, you cannot pick them up on a Sunday.
Florence, is not that big of a deal. Especially if you're not into museums (the Uffitzi isn't all what it's cracked up to be). Some nice churches for photos (the Duomo is one of my favorites all time) and the street side shopping if cool. But outside of that, not much to see. If you like to buy things (leather is big there) be prepared to drop some coin.
Paris is cool...careful of your belongings, my wife had her iphone stolen from there. Plenty of beggars...and people trying to sell you anything and everything. You'll see the same exact painting of the tower, that the person states they painted themselves...by 15 different peddlers. Favorite places, for some reason, seem to be the cafe's with the outdoor tables. Just seem really cool to sit back, relax, and do the cliche things.
Can't tell you much about Munich...
I'll wait to hear from you on how that was.
I'll second the small towns (as listed above). My father-in-law lives in Abruzzo (on the Adriatic) and we have cousins that live up and down the east coast of Italy...my best times are always in small towns, especially when they have some sort of festival going on. My trip to Peru last week was much the same...falling on Puno's "Fiesta de la Candelaria" was an awesome time...if you look it up, there's always something going on somewhere. There was a Tartufare festival (Italian for truffles) in one small town in Italy that we went to...best time ever. Folks in these small town always embrace those around them...and make you feel very welcome.
I really hope you have a great time. Traveling is the best.
