There is also South Coast Plaza - which has more 'high end' stores. But they also have Macy's, Robinsons-May, Saks, Sears and Nordstrom. Plus heaps more smaller stores
It's not too far away - you can catch the bus without too much trouble - South Harbour to Sunflower then change and go down Sunflower. Or there is a shuttle you can order to come to your hotel.
I do love Mainplace too. There is also Anahiem Plaza - which is a bit further away, but it has Ross, Walmart and a few others. (I really like this Ross store - I have got heaps of great bargins from here).
Happy Shopping!!!
I will be there melting the plastic in September!!!