he could walk to DTD and walk around there window shopping and stopping to eat somewhere - it's a huge area - just walking all of DTD can take a while...
then he could take a disney bus from DTD over to one of the magic kingdom hotels (contemporary, polynesian and grand floridian) and then hop on the monorail, which is free..
he could ride on the monorail around the magic kingdom area hotels and then switch to the monorail that goes over to epcot...then take it back...
riding the monorail is one of my favorite free activities....
since he'll be there when xmas decorations are still up, he should check out the decorations in the grand floridian resort....they're especially lovely...
oh wait...you said in the evening...well he could still either walk around DTD, or hop a bus from DTD to the grand floridian - check out the decorations, then ride around on the monorail...
or go to the polynesian (also by bus from DTD) and watch the MK fireworks from the beach at the poly....
or from the food court at the grand floridian....or if you stand on the dock at the grand floridian, near narcoosees, you can see the fireworks and hear the fireworks soundtrack piped in at narcoosees...