Stick around your resort and relax. Shop a bit downtown at sidewalk vendors first, before going over to mall. Bus cost $2.30 round trip each...kids might be less??? take depalm's "Discover Aruba bus tour" from 9 am to 1:30 PM when it is cooler. they have an afternoon one if you prefer. see gold mill ruins, caves, old natural bridge area, old chapel, lighthouse, neighborhoods, and finish up snorkeling for 30 minutes or so at baby beach. they pick you up and drop you off at your resort. see
www.depalm.com for land/sea tours. maybe take the kids to the donkey farm or butterfly farm or maybe on the glass bottom boat. I'm sure you will want to return to Aruba. so save some tours to do on another trip too.