As a NY resident, I've been enrolled in Regents courses since my freshman year, and next year I will be taking 3 AP courses along with my 4th year of Spanish. I am overinvolved in clubs and activities at school, am class president and otherwise well rounded with the exception of athletics.
Competitive colleges look for several things in prospective students.
However, they're basically the same items all colleges look for. When searching for the right school you'll need to ask what specific things they look for in prospective students. Many Ivy League schools require elaborate essays and recommendation letters. Another option is to look through school guides to find out which school is the most competitive and which one's are liberal. You'll find great examples within these guides.