Hi Paulette! It's rare that my Walt Disney World vacations don't include a stop at Downtown Disney. The great thing about this area of shops, restaurants and activities is that you can spend as much or as little time and money there as you want. If you have a free evening during your vacation, it's worth hopping on the bus from your resort to spend a couple of hours at Downtown Disney. My family often goes there to eat lunch at Wolfgang Puck Cafe on our arrival day, or to have an ice cream sundae at Ghirardelli and then browse the huge World of Disney store.
Downtown Disney has several activities that your grandson would enjoy. DisneyQuest, the indoor interactive theme park, is a hit with every kid who enjoys video games. Board the Characters in Flight tethered hot air balloon for a birds-eye view of Disney World. Gaze at the amazing Lego sculptures and construct a few of your own at the Lego store. Build your own custom remote-controlled race car at Ridemakerz. Go bowling at the brand new Splitsville or take in a movie at the AMC theaters where you can have dinner brought to your seat.
You'll definitely have plenty to do in the Disney parks, but if you find yourself with some extra time, Downtown Disney is a fun destination!
Come visit me again at the Moms Panel if you have more questions! I'd love to help!