I don’t know about the California version (someone on another board was saying it’s in need of a rehab), but I recommend checking out Soarin’, as well. It’s a fantastic ride in Florida. Another three weeks and I’ll be back in WDW again for a few days 
Hey, I’m right down the street from it as I type! (I teach at a nearby private school).
Disneyland is still pushing their 50th anniversary, so look for 50 pairs of Mickey ears hidden (some not particularly well, on purpose) throughout the park.
If you haven’t been in 25 years, I’d guess you haven’t seen Mickey’s ToonTown, inspired by the film “Who Framed Roger Rabbit?” back in the late 1980s. That’s where Mickey and Minnie will be to take pictures with.
Oh, and Country Bear Jamboree is gone.
And of course, for even more money, there’s Disney’s California Adventure and Downtown Disney right across the way.
Lessee, looking at this here Wikipedia page, things you might remember that are no longer there are:
Circle-Vision 360
Skyway between Tomorrowland and Fantasyland
Submarine Voyage
People Mover
Adventure Through Inner Space
America Sings
Skull Rock and Pirate’s Cove
Motor Boat Cruise
Mike Fink Keel Boats
Country Bear Jamboree
Mile-Long Bar
Stuff that will be new to you (from here):
in Tomorrowland (which underwent major renovations a number of years back):
a re-vamped Astro Orbitor
a re-vamped Autopia
Buzz Lightyear AstroBlasters
“Honey I Shrunk the Audience”
Innoventions
a revamped Space Mountain
Star Tours (based on Star Wars)
in Frontierland:
Big Thunder Mountain Railroad opened in 1979, don’t know if you rode that.
Fantasmic! light show, using the arcane art of phantasmagoria, the projection of pictures and film on a curtain of rushing water
The Swiss Family Treehouse is now Tarzan’s Treehouse
in Critter Country (formerly Bear Country):
Splash Mountain
Many Adventures of Winnie the Pooh has replaced Country Bear Jamboree
And the Aforementioned Toontown section of the park, with a number of attractions.
Oh, and the whole E-ticket and so on system of ticketing has been scrapped. I don’t know if that happened before the last time you were there.
Oh, and the Indiana Jones ride, which will rock your world
Soarin’
Monsters Inc.
It’s Tough To Be A Bug
Muppets
The Aladdin show
Disney Animation
And the best thing about DCA: alcohol is sold
Although, if you only have one day, spend it at Disneyland.
Buzz Lightyear
If you really want to make the most of your day, you can try RideMax.
Don’t miss Fantasmic! My favorite thing in the park. Go to the 2nd show if there are two. And you can get a good viewing spot without a long wait if you station yourself behind the middle light/sound tower. About 15 minutes before showtime, it rises into the sky revealing a great view.
On my recent trip, we did the coolest thing ever: for a hefty price, you can reserve a seat on the balcony, outside the Disney Gallery, above Pirates. Includes an all-you-can-eat dessert bar. Perfect view of Fantasmic, and the best part is that you don’t have to get there an hour early to get a decent place to stand.
RideMax rocks! I used it last year and it was fantastic. However, they do state that they don’t collect data for Sundays.
I’ve heard vague rumors of a Kim Possible ride or area, either open, or opening soon.
We just got back from Disneyland a couple, three weeks ago. I hadn’t been since I was 13 and I’m now 42.
At any rate, we arrived there on a Sunday and found the lines were not bad at all. In all cases, the lines seemed to move pretty fast, except for Autotopia. That was the slowest line we were in. In fact, the lines seemed longer on Monday.
I’ll add my voice to the chorus extolling Indiana Jones, Space Mountain, Splash Mountain, Indiana Jones, and the Thunder Mountain roller coaster. The other stuff was sort of, um…“meh”. Well, except for Pirates of the Caribbean. I did enjoy that.
I was surprised to read that Autotopia had been revamped. It seemed much the same to me. The Haunted House doesn’t seem to have changed either.
Although I didn’t eat the at the Bayou restaurant, I found the food in the park to be overpriced and not very good. We ate at some mexican buffet type place and were not impressed. It was also expensive. When you take into account there were four of us, it adds up.
If you do have a hopper pass, I have to say Tower of Terror was pretty damn fun. I enjoyed the Grizzly Rapids ride too. Mainly because it was hot, and it felt good to get wet. We got there to late for the big roller coaster there. They were starting to shut down the rides by the time we were done with Tower of Terror and other stuff. My husband was disappointed. He really wanted to ride that.
At any rate, we had a great time and feel like we walked a kajillion miles. We did Disneyland/California Adventures Sunday through Tuesday, Universal Studios on Tuesday, and drove down to SeaWorld on Wednesday and spent the day there. Then we drove home, all the way back to Washington state.
Have fun! We did.
This is probably the last I’ll be posting before we go, but thanks all for the reccomends and ideas. I’ll give a report monday. 
Just a quick note to say we just got back. Had a really good time! I’ll be posting my pics from today on yahoo, user name there is the same as here if anyone wants to see them.