In response to the colonel, The Swiss Family Robinson Treehouse was one of many icons to both the Magic Kingdom and Disneyland. Tarzan's Treehouse...not so much.
I had always envisioned a Wild Thornberrys tree house attraction to be placed in the grassy knoll in-betwixt Phantom Flyers (now Linus Launcher) and Timmy's Air Tours (now Sally's Sea Plane), and have the log ride instead become what would equate to a cross between Splash Mountain and Ripsaw Falls, called Nicktoon Falls. Then again, I had once envisioned a completely different version of the former Nick Universe, what with four separate areas - Jr. Ville, Neutron Plaza, Splat City & Mt. Gushmore, and Bikini Bottom.
Jr.VIlle would encompass the northern quarter, going from Wind-Up to the Snoopy Boutique. This is where a majority of the kiddie attractions would reside (the rest would sit inside BB), however, the Character Carousel would be moved into the area as a new flat ride would take its spot in NP. All rides are based off Jr. shows (Lazytown, Backyardigans, etc.). Compared to the other three sections, this would receive the least amount of significant changes.
Neutron Plaza, themed primarily to Jimmy Neutron, sits on the eastern corridor and is essentially the smallest of the four sections. Sitting in Carousel's position would be an Astro Orbiter-styled attraction for the entire family. The big change here would be the addition/creation of a Festhaus-style indoor restaurant, Nicktoons Cafe, going in the spot of both Ice Cream and Snoopy Grill (Blue's Ice Cream would be moved over to Jr. Ville). Taxi Jam (now Great Pumpkin) would be rethemed to Danny Phantom (with a name of something like Danny Phantom's Ghoster Coaster).
Splat City & Mt. Gushmore resides down south, and is a hybrid of themes. The Wild Thornberrys treehouse concept I mentioned up above would be in this area, roughly where Linus Launcher sits now. Runaway Reptar would stay the same, except the theme would more closely resemble that of an actual episode of Rugrats. What that means is a mix between alphabet blocks scattered about and positioned to look like a cityscape and actual skyscrapers and buildings, to blend that sense of imagination and reality the show is famous for. Also, behind RR and making its way into Nicktoons Falls, is a faux mountain range with the Nickelodeon letters in the style of the Hollywood logo. That mountain range carries its way into Mt. Gushmore and Nicktoon Falls, a heavily rethemed log ride built similarly to Splash Mountain. The focal point would be a rock formation of five famous Nick characters (Tommy, Jimmy, SpongeBob, and the Fairly OddParents) like Mt. Rushmore.
Bikini Bottom is the last section, to the west, and is the biggest change to NU. The inspiration for BB comes from an attraction called Mermaid Lagoon at Tokyo DisneySea, which is an indoor kids area made to look like everything is underwater. The same concept would be applied here, as people would feel as if they were underwater, and in the town of Bikini Bottom. The star attraction here is the Crash Course Boating School, an indoor/outdoor dark ride/coaster. Other notable attractions would be offshoots of ones found at Mermaid Lagoon, such as a Jumpin Jellyfish parachute ride, and a clone of a ride from Great America (Boatmobiles, now Peanuts Pirates).
This is all I can remember for the time being, as I had this all planned in my head years ago. Perhaps I should try and create this in RCT3...
EDIT: I would have had a crudely drawn picture to illustrate the zoning, but it won't let me put up the picture.