When I was on a recent vacation to San Diego, I decided to check out the San Diego Zoo. I planned my trip in advance and booked my hotel close to the zoo. I got some cheap tickets on groupon.com with a couple of my friends from college. I went during the holiday season so there was crowded lines. The best apart of the Zoo was definitely the sky tram. The tram goes over the entire zoo giving you a birds eye view on the whole park. If you come to the park, plan in advance so that you can get cheap passes and avoid the long lines.