Ooh! Have fun, Fren!
And in Paris, one word of caution: try to speak French to the shop keepers and natives FIRST. Many of them do speak English, but they will be more rude and possibly even over-charge you intentionally if you don't at least attempt to speak their language. I was there about 12 years ago and the shop keeper acted like he spoke no English to the couple in front of me, then corrected my French pronunciation and then proceeded to have a pleasant conversation (in English) with me about how rude American tourists are when they just assume that everyone all over the world should speak their language! (then he gave me a small 5 F discount.) I also spent 5 days in Nice, France on the Mediterranean coast - where most people really don't speak English. Beautiful place! Not as dirty as the big cities.
Having never been to Rome or anywhere outside of the Airport in England, I can't say anything about them. Just try to speak the language where ever you go. Even if the only phrases you know are "where's the toilet" and "do you speak English?"
Think about how you perceive foreign people who just walk up to you and start babbling their language, arrogantly expecting you to know what they're saying. American's have a bad rep for arrogance and rudeness in most foreign countries already, no need to make it worse I say!