Welcome back! Always fun to have a Disney trip to plan
I love HKDL! Just such a fun, low-stress kinda place. With that in mind, you won't need to do much planning - with 2-3 week days in the park you should pretty much be able to do everything multiple times with plenty of time to just take things in. I've got 1-2 days there in October. Book-ending this trip with DLP at the beginning and HKDL at the end. It won't be my first visit, but I haven't been since 2019 so a lot has changed. I'm sure it's probably gotten busier since I was last there too, but still gets regular mentions as the least crowded park with plenty of very reasonable wait times. This is my plan:
Rides:
Big Grizzly Mountain and Mystic Manor are 2 of my favourite rides at any Disney park, so my plan is to pretty much ride them on repeat. New since my last visit will be Frozen land and the rides there, the Antman ride and Space Mountain re-theme. I also enjoy the Iron Man ride, which is fairly unique to HK (using the Star Tours ride system). Most other rides are pretty much clones from other parks, but of course I'll still partake if there's a good opportunity. Fairytale Forest is also a cute little walk-through attraction and worth doing if you've not been before.
Shows:
The Flights of Fantasy parade was my favourite of any Disney park, so I will definitely be making sure I get a good spot for the new Friendtastic parade to see how it compares. Mickey and the Wondrous Book is awesome, broadway quality and well worth seeing. The theatre does fill up, so make sure you don't leave it until the last minute if you want to see it. Momentous (evening show) looks amazing, and I'll be making sure I get a good spot for that too. Festival of the Lion King is pretty similar to the one at WDW if you've seen that. I will be coming from DLP, which also has a Lion King stage show, so I probably won't prioritise that one, but you might want to. I haven't really bothered to see the Moana show previously, so I might make the effort this time. The castle stage show seems to be a 20th anniversary thing, but they might keep one going when the anniversary finishes up. I've always enjoyed the roving entertainment around the park too.
Characters:
People get really into the characters in HK, and the lines for the character meets on Main Street can get pretty long. I can almost guarantee the wait for Duffy and Friends will be the longest in the park. Gelatoni is one of my favourites, and I'll be Disneybounding as him on one of my days, so I'll be doing my best to meet him, but won't bother with any of the others. I've had better luck with the random character meets throughout the park, or even the ones in Fantasy Gardens, and have had some of my favourite interactions there.
Other considerations:
The merch has been next level on my previous trips to HK, so I'll be allowing plenty of time (and money!) for shopping. Most of my favourite purchases have been from there. They also have lots of cute food items. I used to love the Minnie ice-cream bar, which is strawberry and mango ice-cream with chocolate just on the back. I've also enjoyed pin trading and generally interacting with the CMs - they just seem to have a different energy there.
I'm going during Halloween time, so I'll also be doing as much of the special Halloween stuff as I can. There is often some kind of special event happening - there might be something on for spring time during your visit.
Not sure where you're staying, but there's also lots of fun things to do and see at the hotels. The
Disneyland hotel has a fairly popular Disney dim sum available with prior booking. I'm staying at the Hollywood Hotel and Explorers Lodge and looking forward to wandering the grounds, looking around the shops and seeing if there's any characters hanging around. If you get a chance, the walk between the hotels along the waterfront promenade is quite a nice thing to do. The walk from the hotels to the parks is also nice and quite easy - personally I'd never bother with the crowded shuttle bus.
We have a wedding in the Philippines first then a couple of days on the way back in HK DIsneyland!! couldn't think of a better way to finish a holiday if you ask me. 
