Interesting question:
Epcot-
First, I would add Spain, India and/or Australia to the World Showcase. Plus, I would add at least 1 new country every 5 years while phasing out old or tired countries. Yes, I know it's alot of work but families would go back to Epcot to see the new showcase. Each display would have a major restaurant, a major "presentation" (like a 360 degree theater), and an interesting ride attraction that fits it's individual queue (like Norway has now).
Second-As for the "future" part of Epcot, I'm not sure you can maintain a "futuristic" park-what I mean is the advances in science and engineering are so fast now-the display's you put in this year will be outdated next year and look just lame in 2 years. I think I would keep that general theme but have more attractions like "Soarin" and "Mission Space" instead.
Third-Speaking of Soarin, I would double the amount of apparatus that Disney has right now for Soarin as there is always a line that is usually over an hour long.
Fourth-I would not tie-in to Disney shows with any of my attractions. For instance, that "Kim Possible World showcase Adventure" is a perfect example. Is Kim Possible even still on? My kids watch Disney 24/7 and I never see it. They didn't know who Kim Possible was so I don't think tie-ins work very well.
Fifth-I would get rid of Captain E/O. It's just old and it's star has passed (God rest his soul) which just makes it somewhat creepy for me.
Animal Kingdom-
First, I'd complete the park. I know AK is all about animals but in my opinion, It needs at least 3 new attractions. A couple of rides and at least 1 new show. The whole zoo vibe is OK but you've got to add some stuff to do. It also needs a couple of new restaurants. I love the villages and the current queue's but it's just lacking.
Second-I'd re-tool Dinosaur-This ride was disappointing to me. The queue was weak and it shook too much and just didn't seem.......fun. There has to be a way to make it better.
Other than those suggestions I think AK has it's own "interactive" animal attitude-I get that but we don't even plan to go there on our next trip because it's just....not that fun. Simply.....it needs more stuff.
The Magic Kingdom-
First-I would install a whole new roller coaster in Space Mountain. That ride is lame, old and outdated. An old roller coaster in the dark....uuugghh.
Secondly-I would get rid of Stitch. I have never met anyone who defended that attraction.
Third-I would add a couple of shops on Main Street that don't sale high priced shirts and hats. Maybe like a magic shop or something.
Fourth-I'm sorry but I would get rid of or at least re-tool the Carousel of Progress-At this point it just looks sad and the mechanics look extremely outdated.
Overall, I think this park needs the least amount of renovation as it is an icon for families with smaller children and should remain that way. However, I do think it needs a new major ride to spice it up every 4 years or so.
Hollywood Studios-
First-I would close the Narnia Prince Caspian thing-NOW, on the first day. My goodness, that movie is 4 or 5 years old and still an attraction. That is just lazy and moreover LAME!!
Second-Muppets Vision 3-D-You know, I grew up with the muppets but I'm 47 years old. My kids didn't know who they were. I'm not saying I'd get rid of it but it...just...is not really current.
Third-Sounds Dangerous with Drew Carey-Hmmmm, this gets back to my tie-in issues. I liked Drew Carey but does he fit Disney....I'm not sure he does.
Fourth-The Studio Backlot Tour-I enjoyed this but it needs....something. Maybe a little updating. I wouldn't get rid of it but just spice it up.
Fifth-The Great Movie Ride. I'm sure this was a great ride, 20 years ago. Again, just update it with some current movies and improve the mechanics as it has a Carousel of Progress feel to it.
I love the overall feel to Hollywood Studios. It just needs some new attractions. It needs a major new ride and a new show every 4 years or so. It could also do well with a couple of new restaurants too.
Other things Disney could do:
Set up a Disney "Disney Express" at Sanford Airport. We wanted to fly an airline that lands there but the airport has no Disney transport. It doesn't have to be the size of Orlando international but anything would help.
Discontinue tipping at the high end restaurants. Here's the thing-I spend several thousand dollars to come to Disney and then I have to shell out another $20 to $40 every time we eat at a high end restaurant even though I've already paid for eating there with the meal plan. The servers are great but it's just not very festive for me to have to carry around cash when I've prepaid my trip already for tips. Maybe it should be part of the meal plan.
As I have said many times-I love Disney. There is no better place for a family to go. But, if they asked me to add to the re-design, these would be my suggestions.
