Good activities for the summer are anything that allows you to engage with an interest, people, a new skill, a sport, an academic subject, a work environment, etc. There is no one right thing to do in the summer. I encourage students to participate in activities that they enjoy. A summer job means as much as taking a class at a college. And taking a class at a college doesn't have to be by participating in an expensive program. It is just as impressive to take a course at a community college as it is to pay thousands of dollars to take a class at an elite private school. The important thing is that you are using your time to grow, learn, work, give back, or participate in something that you really enjoy.