Hi Kim,
As a fellow Disney lover, I think a tour is an excellent idea! There are some incredible backstage tours that will give him an in depth look at what goes on behind the scenes. These tours do require a bit of walking but all of them are handicapped accessible & you could rent an ECV for him to use during the tour. I've been in tour groups with guests using ECVs & the Cast Members were super helpful & accommodating. Here are my top suggestions.
Backstage Magic Tour - my personal favorite. This takes you behind the scenes of all 4 theme parks, Central Shops & WDW Nursery & Tree Farm. This tour also includes a trip to the utilidors in the Magic Kingdom (MK). Its a 7-hour tour but it goes by incredibly fast.
Disney's Keys to the Kingdom Tour explores the stories behind the remarkable creation & growth of the MK. This tour lasts approximately 4 1/2 hours & also includes a trip to the utilidors.
Walt Disney: Marceline to Magic Kingdom Tour is a 2 1/2 to 3 hour tour where guests hear how the town of Marceline, MO inspired Walt to create Main Street USA & how events in his life turned into attractions & innovative touches seen throughout the parks.
I'm limited in space but
here is the link to all of the tours. I'm happy to answer any additional questions about these tours.
Another option is
Dining with an Imagineer which gives guests the opportunity to dine with a Disney Imagineer at either The Hollywood Brown Derby restaurant at Disney's Hollywood Studios (requires theme park admission) or the Flying Fish Café at Disney's BoardWalk.
Wishing you minnie magical memories :-) Allison