Well, he's not going to totally avoid children. We have been going since the kids were little - they are now both in college. Here are some of our not-so-kid oriented favorites:
MGM/Disney Studio
Great Movie Ride
Indiania Jones Stunt Show
Fantasmic
Tower of Terror - but take the chicken route if you don't like rides...you'll be able to see the theming but can skip the "ride"
Motorcars Stunt Show
Backstage Tour
Beauty and the Beast Show
Magic Kingdom
Hall of President's
Pirates of the Caribbean (a ride, but very calm)
Jungle Cruise (same)
It's a Small World (same...unless you don't like singing)
Tiki House
Peter Pan
Train that goes around the park
Mickey's Philharmagic
Animal Kingdom
It's a Bug's Life
Safari Ride
Conservation Station
Festival of the Lion King
Any of the trails
The bird show? - not been to that but heard it's nice
Epcot
Energy Adventure
Spaceship Earth
Living with the Land
Soarin' (it's a ride, but quite awesome!)
World Showcase (including American Adventure)
All of these parks have shows, parades and various street entertainers ... it is a must to get one of the entertainment guides and take a look at what you might be interested in seeing and then base your touring on that so you aren't having to walk too much.
You find that some of the attractions in World Showcase will have you standing to watch a circle-vision show ... if you are elderly this may not be something you choose to do. Ask at the entrance if you don't know.
There is lots to see, people to watch, food to eat, stores to shop in, and many, many benches throughout all of the parks.
Don't forget to check out the Boardwalk for some evening entertainment - there is a piano "bar" for adults only as well as ESPN Club. We enjoy Bob Jackson at the Riverroost Lounge, Port Orleans Riverside - he does a show which is free from Wed-Sat each week. There will be some children, but it is a bar so you can drink enough to soften the blow. Mostly, it is adults acting like they are children though.
Don't forget that you can always ride on the ferries in the Magic Kingdom area (I know you said no water, but assume you mean water-rides). Especially if the weather is nice out, there is nothing more relaxing than to ride one of the resort launches to and from the various resorts (Poly, GF, CR, Ft Wilderness, WL). Remember that Port Orleans also has a boat from their resort to Downtown Disney which takes you by the golf courses and docks near the Rainforest Cafe.
You'll have a great time ... lots to see and do!!