Every school has service opportunities. When you are in school, though, what you'll really want to be doing is studying. If you spend your time doing community service, you'll want to do it whenever works best for YOU and not according to a school's schedule.
I had to do a service project for my school and it was the biggest waste of time ever. Plus it fell during a course that was difficult for me. On the other hand, I did community service on my own with an outside organization every week on a day that worked better for me, and could skip it when I was behind in school.
My point: if your school is in a city, you don't have to worry about whether the school has community service opportunities because community organizations have better opportunities than the schools. The schools have a few important standard projects that are at every med school, plus a few extra projects to make themselves look good but which aren't very important for the community.
Also, for some reason, EVERYONE thinks that their school has the best community service opportunities. They all quote free clinics or trips to the Dominican Republic or a rotation in Haiti. I can assure you that in reality, every school has these things. They are not distinguishing factors.