Thank you for your suggestions! I'll have a closer look at them.
We'll certainly visit San Diego Zoo and the USS Midway. I guess, these days can be filled with strolling around some of SD's neighborhoods for dinner etc. Or is it necessary to plan a full day for the city itself?
One day will be dedicated to shopping. Is there any preference between the two Premium Outlets in Carlsbad and at the Mexican border? The latter can be reached by trolley, right?