I think the ART will take you to the Block at Orange - an outdoor mall that has several mall stores. There is also the new GardenWalk in walking distance. We haven't been there yet, but I'm assuming it's like the Grove, Paseo, and Americana - both upscale outdoor shopping with finer dining and outdoor activities. I'm not sure what kind of transport would take you to the Irvine Spectrum, but that place is a fun outdoor venue, too - about 10/15 minutes away.
There are other malls in the area, although not quite as close. I just ccan't remember the names of them right now. (I live in the Valley and not Orange County, so I've only been to a couple of them in passing.)