As a current US student, I can tell you that Cambridge and UC Berkeley are both FANTASTIC schools, and roughly equal in terms of international rankings. While it's not "Ivy League" (the term actually refers to a sports conference from schools in the Northeast, it just so happens that they are all academically outstanding private universities), Berkeley is undoubtedly the best public university in the United States, and is ranked higher internationally and domestically than most of the members of the Ivy League.
UC Berkeley is also in one of the most desirable and beautiful (if expensive) areas in the US: the San Francisco Bay area.
You would receive a world-class education at either university, however, being inclined to international study myself (I'll be attending the University of Edinburgh this coming year), I would recommend you experience another culture in the US and come to UC Berkeley if you can afford it.
Also, as a word of caution, don't put too much faith in rankings. Most of them aggregate based on research, which only affects the postgraduate level, and certainly wouldn't affect your undergraduate education or the quality of instruction you would receive at any university. Especially with UC Berkeley and Cambridge, the difference in academic quality is really nonexistent. Go for the school that YOU feel most happy with.
Feel free to PM me if you have any questions.