Riding for something meaningful

I've always had some sort of internal debate regarding rides for charity. Is it better to just donate the money yourself, or to go door to door collecting pledges for a ride? Or, rather than joining an organized ride, is there a more substantial goal to raise funds through?

My first dabble into pledge collection was for jump rope for heart, a program in my elementary school gym classes. 6th grade saw the mathathon, a fundraiser for tsunami victims.

Now, raising funds on a journey across the gulf coast and through the southwest.

Who should I ride for? 

Requirements: 

Involves cycling, and ideally youth

Serves underserved populations