Alright, I've given it some thought, and after reading all the comments, I've come up with a plan of how I'd update Tomorrowland. Unfortunately, it involves changing nearly everything, but since the thread title does say "makeover", I guess it works.
Here's my idea:
Aesthetics -- keep the current "feel" of Tomorrowland, but try to do a better job of translating the nighttime look/colors (Disney Tourist Blog has a great photo set of nighttime Tomorrowland
here) into the daytime. Right now, during the day all you get it a lot of metal, navy, and muted blues, greys and purples. It would be fun to bring in brighter colors, like the lime, red, and bright purples of the nighttime neon by updating the paint and accents in the land.
As someone else pointed out, there is a stray bathroom to the right when you face Space Mountain that doesn't have any anchoring point. There's actually a lot of odds and ends trying to fill up space, mainly the Buzz meet and greet on one side of CoP, and the Dance area (Club 626?) on the other side. I would scrap the dance floor and buzz m&g, and instead build a permanent m&g building by the restrooms where guests can meet a rotating group of "galactic friends" (Buzz, Stitch, Space Chip & Dale, etc.)
Attractions ---
Keep Space Mountain. Refurb as needed.
Carousel of Progress- Keep, but update exterior to be a little more inviting. Right now the colors and signage look a little dated. It really fades into the background compared to how busy the rest of the land is. I believe you can see the sections rotating from the outside? If so, I would maybe go for a bright, solid color paint instead of the gears, with each section a different color with a quote in white about the future from either Walt or the Carousel show itself. As the carousel moves, you get a new color and new quote.
Tomorrowland Transit Authority - Another keeper, though I might update the look of the cars... right now it looks like they painted a couple of Sterlite bins blue, added some wheels, and hitched them together. I wouldn't make any changes that would compromise the integrity of the system (like the ill-fated Rocket Rods), but even some small cosmetic additions or decals could go a long way to making it more "futuristic".
Stitch's Great Escape: I would do a major overhaul of this ride. Stitch belongs, but his ride is atrocious. Keeping with the current makeup of the ride, I would get rid of the "escape" story and instead put in a "monster/alien" lab. The general premise is that Dr. Jumba has made an alien laboratory on Earth without the knowledge of the galactic federation, and he's showing you how he made Stitch and other aliens. The main show room has the same circular layout of the current ride, but panoramic screens would be installed in the whole theater, set higher on the wall so it looks as though Jumba, Pleakley, and Stitch are talking to you from behind glass on the second story of the lab (they would be in CGI, not traditional animation, for more "realism"). They would circle the whole theater as they go through the demonstration, building an alien in the tube at the center of the room (alien would be projected).To make it interesting, Jumba would ask for input from the audience on how to build the alien, covering basic attributes like size, color, how many arms/legs, if it should have antennae or wings, etc. The audience would choose using buttons installed on the armrests of the seats. At the end, you've built an alien, and Stitch, being Stitch, accidentally lets it free. Room goes dark, alien disappears, lots of crashing and smoke ensues, and when the lights come back on Jumba explains that they have to go find the alien, etc., etc. (though i would really love if he ended with a line like, "and now my alien monstrosity will follow you home mwhahaha" ala Haunted Mansion. New Name: Stitch's Monster Maker? Laboratory 626? (I'm not sure here... they aren't monsters so much as aliens, but it's hard to come up with a good alien name)
Tomorrowland Speedway - Scrap it. In its place, I'd either put a completely new, non-IP ride or Sugar Land Racers. I debated on Sugar Land because it isn't really futuristic, but I think it would go perfect in that corner. Instead of a traditional car-on-track ride, I would make it into a Star Tours type simulator, with 4-8 different tracks/courses you could potentially ride on (all with Vanellope). The pre-show would have Ralph trying to teach you how to be a racer (since, as we observed in the movie, he clearly is an expert at driving ; p). The entrance to the ride would be in Tomorrowland and would be themed like an arcade with a bunch of Sugar Rush posters (for example, there could be signage saying "Litwak's Arcade, now featuring Sugar Land Racers"), so you get the Sugar Land connection without completely breaking the theme. You enter the arcade, and the queue has arcade games along the walls in a room, with you eventually walking "into" a Wreck it Ralph game, going through a Niceland themed room, and then coming out into Game Central Station before boarding to go into Sugar Land. The exit is a completely sugar-coated gift shop and candy store that opens into Fantasyland, where the over-the-top Sugar Land theming is more appropriate.
Buzz Lightyear's Space Ranger Spin - I like the ride itself, but I feel like it needs major updates. I would like to find some balance between the 90s glow in the dark shooter and the technologically cool, but logistically terrible, Midway Mania. I don't want to turn it completely into Midway Mania, because I like the current omnimover set up and my arms can't take another pull-string cannon... but a balance would be nice.
Monster's Inc. Laugh Floor - I would scrap this one as well. Instead of a ride replacement, however, I would expand the building to merge with the kitchens of Tomorrowland Terrace next door, and make a restaurant. I'm not going to lie, that whole area confuses me to no end (it's a noodle station... but there's also a table service restaurant... but it's not really a restaurant, it's an outdoor buffet? but there's also a cafe? but its all only open maybe 3 months out of the year?) All I know is that, 90% of the time, it comes off as this odd dead spot when you walk that way. To make things simple, I'm taking the kitchens, but leaving the seating. This way, dessert parties and special events are still doable, and guests can still have the extra seating for when the 3PM "please get me out of the sun before i strangle someone" mood hits. The restaurant would be table service, mainly because Cosmic Ray's already provides a quick service spot. It would be themed as a planetarium. I'm not sure whether to go "serious" or "fun" with the theme... regardless, the ceiling would have a moving projection of outer space, so you can "eat under the stars". If we go the fun route, I totally envision alien saucer-shaped booths to sit in... but that may be too much. Cuisine would be fairly standard, kid-friendly stuff. Between the exotic Skipper Canteen and the fancier Be Our Guest, I think a more accessible/familiar menu would be okay, as long as it's done well with a couple of twists to set it apart from standard counter service-fare.
Other than all of the above, though, I think Tomorrowland is fine staying as-is ; )
