I usually take the wife to Chatuchak once per trip, but she always enjoys shopping at Platinum and Patunam malls for most items, then follow-up at MBK. In my 50 odd trips to Bangkok, have rarely bought anything at Terminal 21, Central World (used to be World Trade Center) or Siam Paragon, other than food.
Grocery shopping we'll do at Robinsons, Foodland or in the malls.