DontPanic1, economics is a class for the waitingforcal's major (business), so like you say, he should probably avoid it for now.
I have completed community college courses over the last 2 summers. On both occasions, I worked part-time. The first time it was 6 units (2 courses); the second time it was 5 units (2 courses). It seemed good. I could have probably done an extra class, but I wanted to devote more time and energy to fewer. As a result, I've earned As in my summer courses. All my summer courses have been GEs.
If you want to take an economics course, as you pointed out, there is Macro and Micro. My college places Macro before Micro. I've completed both courses. Macro can become more difficult than Micro, in my opinion. Summer may be good for Macro since you can devote more time to it, and classes almost everyday, so you forget less/remember more.
Overall, my opinion would be to enroll in GE courses for the summer. Most people do, and some of the time it prevents you from taking a semester of communication/art class that really does not require a whole semester. On the other hand, you can take a science course. I did this and it was great, except for the 4+ hour lecture/lab, back-to-back thing. It was better than a crazy semester with an awkward schedule, though!