What an exciting trip!
When you say you're just planning to spend one day at each resort, do you mean you'll literally be flying in, visiting the park/s, and then flying out again, or do you mean you'll be spending one day at each resort as part of your stay at that destination (so you'll have a few days in each place, one of which you'll spend at the Disney resort there)? It seems like you're not planning to spend long at each destination, so be prepared to be absolutely wrecked by the time you get home. Business class flights between continents will help if you can get them
Can I suggest you consider doing one day for each park at TDR, as they do not offer park hoppers at this point. TDS sounds like it's absolutely worth visiting, being very different to other parks and widely considered the best in the world. However, if you're aiming to get a photo in front of each castle (which I would absolutely do!), then you would need to do TDL.
Unfortunately there's not a whole heap of info on SDL or HKDL. They're relatively easy to manage though, just being one park, and HKDL doesn't even have a shopping/dining district. If you're staying onsite, some of the hotels are walking distance, otherwise the buses are very easy to use. If you're coming from the city, the trains are pretty easy to manage with the stations very close to the park entrances. Any threads for either of them will be posted in the general 'Other Lands' section, and that is where you can also ask any questions. There are quite a few of us now who have been to both, although for me it's been a while! You'll probably need a plan of attack at SDL as it is a very large park which can get pretty crowded with long wait times. However, HKDL is pretty easy to just wing it when you get there - I've never seen more than a half hour wait for any attractions.
With such little time in each park, I would try to focus on what's different about that park. Some of the parks also have rides or versions of rides that have been discontinued in the US.
- Paris: Definitely visit the dragon under the castle, and maybe even do the cute castle walk-through. The Alice maze here is a bit of fun, themed to the animated Disney version. Their Space Mountain is pretty cool and different to all the others, and I think is now Star Wars themed. Phantom Manor is also a bit different to the other Haunted Mansions. In the Studios, there's the Avengers rides, and Crush's Coaster was pretty different and a lot of fun.
- Shanghai: Definitely, DEFINITELY prioritise Pirates! It's the most amazing ride with incredible special effects. The ropes course is also very unique to SDL and gives a nice view over the park, although it's a slow-moving line so can get long, and can take a while to actually do as well. Their Alice maze is pretty impressive, themed to the Tim Burton version. Voyage to the Crystal Grotto is cute and unique to Shanghai - it's particularly nice at night. I never got to Roaring Rapids, but it seems like a re-theme of the rapids ride at DLR. Peter Pan has had an upgrade, but is basically the same as what you'd be used to. I'd do them both if there's time, but otherwise they can probably be skipped.
- Hong Kong: Mystic Manor is great and very unique. Big Grizzly Mountain is also a lot of fun. Similar to Big Thunder Mountain, but I think different enough to be worth prioritising, particularly as there's not much else unique to HK. Fairy Tale Forest is cute and worth a walk-through. A lot of the other attractions are 'same-same but different'. Having said that, the new Frozen expansion will probably be ready for your trip and will have 2 new unique attractions. It's a lot of fun interacting with the CMs and collecting stickers from them if they're still doing that.
- Tokyo: I'm currently planning my own trip to Tokyo. Very keen to try the new Beauty and the Beast ride at TDL, and the Monsters Inc ride looks like a lot of fun. Pooh's Hunny Hunt is by all accounts the best version of this ride with extra effects, and their version of Splash Mountain still has the original theming. At TDS, I'm keen to try Journey to the Centre of the Earth. The Nemo ride and Sinbad's Voyage are also unique and look like fun. Apparently ToT is worth doing as it's a completely different storyline and experience, and they still have 20,000 Leagues Under the Sea if you're nostalgic for that one. There are also a lot of traditional (but Disney themed) amusement park type rides in this park, and a lot of transport options which would be fun to try out.
There's also shows and parades (which you may not prioritise given the short timeframes!). For some of the Asian parks, the stake-out begins very early! I would definitely recommend spending the extra money and utilising whatever 'priority' system each park has for both rides and shows if you want to do them. The Asian parks also do a lot of unique character greetings in different outfits, and Duffy and friends are BIG. It could be fun to do some of them if you have time, or even just get some photos from the sidelines if you don't have time to wait.
As for souvenirs, I know that every park does pins, so I would probably stick with that. As well as the photo in front of each castle of course!
Glad I still have my little collection of stickers from back in the day!
