Two things you can consider for a summer experience that might help you with college applications and eventual acceptance are 1) doing what you love and have interest in and 2)working at a regular summer job. Admissions people want to see that potential students really care and are excited about their interest(s). If you love the ocean, taking part in an ocean institute internship makes sense or helping teach scuba diving at the local YMCA can demonstrate commitment. Admissions people also understand the fact that some students have to make money during the summer. Even washing dishes can provide an experience from which you learn.
Two things to worry about when deciding on a summer experiences with college in mind are 1) participating in a program that is basically a vacation or is only decorative and 2) doing something that smacks of economic privilege. If you go to a Harvard summer program, make sure it has substance in itself and for you. The name on the program is not enough to prove you’ve had a valuable summer experience. Also, socio-economic status might allow you to go abroad to perform social service, but what if the area you live in at home has need of services and you have ignored that? The ability to do is not enough to convince you have done.
Mostly, make sure the summer experience you take part in actually shows your substance and demonstrates that you can be honestly engaged.