Okay to start off, if you've never been to animal kingdom when you pick your day to go make sure you get there really early in the morning and go right to the safari ride that they have. B/c it's not that hot yet and most of the animals will be out so you can see them. And that goes for the walking tours too...after the safari when you get off I would go right to where you can walk and see the animals.
You said that you were having lunch at the crystal palace. If you should ever eat at cinderella's castle, if you want to do something special for your wife call ahead and tell them that it's the honeymoon you never had and if they could recognize that for your wife. During your meal, they'll give you champagne glasses and the fairy godmother will come up to you and congratulate you...it's really neat
Also, all the parks have parades around 3pm. All of them are a must see, along with the fireworks (animal kingdom doesn't have fireworks). Magic kingdom has a lights parade at night, that's something that you don't want to miss. Don't worry about getting to find your seat early for the parade b/c disney has sections set aside for wheelchairs and the families. So you'll get a good spot no matter what.
And you're right, you won't have to wait in any lines with your mom in a wheelchair. But if you should want to venture off with your wife for an hour, fast pass is your friend. They have machines in the beginning of the rides where you stick your pass in there and you get tickets to come back a certain time. When you come back at the time specified you go in a special line and they take care of you first then the others that are waiting in a regular line. This goes for rides and most shows. You might want to get these passes for the rides that have the longest waiting time.
When your in downtown disney the only thing i have to say is go to the marketplace. There is an icecream shop called giradelhi's (sp?) It's the best ice cream you will ever have.
Oh and if you're renting a car, get directions to the town of celebration. It's right outside of disney (literally). You won't regret seeing this town. It's right out of the movie pleasantville.
if i think of anything else i'll let you know.