Have you considered visiting the San Diego Zoo and Balboa Park while in San Diego? You can easily spend a couple of days there.
We have many friends from the UK and shopping is always on the agenda! You can plan visits to several outlet malls (i.e., Ontario Mills, Cabazon, Carlsbad Premium Outlets) just from Anaheim to San Diego.

I don't know which part of NY you're visiting, but my favorite outlet there is Woodbury Commons which is about an hour or so north of Manhattan.
Have fun visiting and planning!