I Lived in the US for 6 years and some of the friends I made are in Ivy League schools now (Princeton and Yale). And I'm sorry to tell you it's not like what you see in the movies. First of all, the drinking age is 21 and states in the north-east take this very seriously so you can indeed be kicked out of uni for drinking. Second, From my experience in the States I can tell you parties actually suck (on a general basis compared to England) because America has no where near the free spirits that England does, Except in certain areas like: San Fransisco, Boston and Miami.
And lastly, One of my Pals goes to the University of Georgia which was ranked #1 American party school by Playboy magazine. And he said the parties there are nothing like what you see on American Pie so not even the stateside's finest can live up to the illusion that these silly movies have given the world.
Nonetheless, the partying may be lamer but that doesn't mean you wont have as much, if not more fun in an American school. For example, American schools are crazy about sports so if your keen, you can make it into a NCAA team which will have its games shown on TV! Also, Car insurance and Fuel is a lot cheaper so if you have that dream of driving while in uni then the US is the place to be.
In my opinion; none of the benefactors can outweigh the cost of American universities which is easily up to $40,000 per year which is around £25,000 and paying off loans after uni in America is actually a struggle whereas loans in the UK are like pocket change.