Recommend Icon Siam for a shopping eating visit !
Go into the basement level for good food set out like a floating market.
Browse shops upto floor 7 for Starbucks, go onto their deck for jncredible views over the city.
Evening, consider a dinner cruise, this has plenty of food beer etc, live entertainment and all the sites and illuminations of Bangkok. Well worth the price.
If you head there for lunch, browse the afternoon, early evening they do a music lights and fountain display, wait short time then board the boat for 2 hrs trip.
The following is in Thai but you'll get a feel for it......