I trend towards suggesting to try everything once for yourself. For RRR and Hulk, you'll be able to see most of the ride for yourself before you get in line and decide then. If you tolerate RnRC fine, you can likely tolerate Hulk. Someone who gets queasy on RNRC might want to skip it. Mummy is no big deal. The only thing is that it breaks suddenly- don't let your head hit the backrest! Coaster part isn't intense except for HARD unexpected breaking. Think of the VERY end of Big Thunder, when you are pulling into the station of Big Thunder - that type of hard breaking.
At Universal, the really water rides tend to be really wet. Most of the time we skip them, especially in winter. They are often closed if it is cold, especially Bluto's. I'd say the way to ride them is to specifically dress to get wet (like wearing a bathing suit under your clothes, no denim ) but i think ti is just the 3: Jurassic Park (not that great, dated), Rip Shaw Falls (dated!, not super immersive ride mostly just to get wet), Bluto's (a little like Kali, but wetter and better themed, fun!!)
Oh, you can also get a little wet on One Fish, but it is very fun. Even on pretty cool days, we've ridden it. It is an aerial carousel like Dumbo, but more fun. If you listen to what the song tells you and watch, you can avoid getting wet.
There's also an opportunity to get wet over by Woody Woodpecker, but I strongly suspect that area is closed now, and might be gone for good. The best part of the area was the room with soft balls you could shoot at friends/family/strangers, except well, it was never all that sanitary to shoot balls that had been rolling on the ground. In front of the ball room was power squirt guns, and a kiddie splash area.
Best parts of US and IoA are the 2 Harry Potter areas. They are as good as anything WDW has built, maybe better, especially Diagon Alley. Do take time to look at all the details. It is $$, at approx $50, but the wands are great fun. Go through the Olivander's experience to get one. And really, once you have one, you can share it in your family. Good news is if it ever stops working Universal will repair/replace it. Also take time to explore all the shops and eateries. Wands are awesome at night!
If anyone in your group is age appropriate for flight of Hippogriff, ride it while you can. It is fun, but you need to have a child of a certain height in your group to ride it. Loading is slow, so pick early in day or when line is short.
Other top attractions include (though this is no specific order): Hagrid's Motorbikes, Escape from Gringotts (awesome, just loud!), Velocicoaster (not yet!), Minions(!), Jimmy Fallon, Spider-Man, Hogwart's Express (fun both ways), Kong (ride multiple times, slightly different each time)
Others: Flight of hippogriff,, Woody's Coster (think Goofy's Barnstormer, except Hippogriff is better!), E.T (neat, but a bit dated), Shrek 4D(a llittle bit of hard breaking, but fun), Transformers (spins a bit too much, could/should have been a better ride), Doom's Freefall (one of those big Space Shot amusement park drop rides), Seuss Carousel, Twirl N Hurl (aerial carousel, but extra fun!), Men in Black (spins a bit much, but FUN! DO follow the ride directions they give you! LISTEN to preshows to get the high score info!), Storm Force, Cat in Hat, High Trolley Ride
Simpsons is just meh. Too bad. Fast and Furious is closed, maybe for good. No big loss. Cars outside the ride are worth looking a moment.
Do see the Animal Actors show, Horror Make-up show, Bourne stunt show, and the Harry Potter shows. Poseidon's Fury takes time, but is worth seeing at last once. We tend not to do shows that much, so we happened to have skipped the rest. If they bring back night shows, fireworks, castle lights - all are worth seeing.
Among the best eateries are: Mythos (If you like risotto, special is often great, lots of good choices), Three Broomsticks (big platter is okay, love pulled chicken platter- it is only listed on the second menu they have at the register), Leaky Cauldron (Go with Bangers and Mash!), Ice cream shop in Diagon Alley, Drinks stand in Hogsmeade, Cowfish, Toothsome (especially the desserts that re in the chocolate shop. The ice cream stuff is all too huge, but the macarons and fine chocolate shop side treats are super!), Finnegan's (where else can you get Irish boil in a theme park!), Fire-Eater's stand kebabs aren't huge, but they taste decent. Sushi at Royal Pacific is great- but only open certain hours. Italian eateries at Portofino are decent, not super, but okay.. We haven't tried all of City Walk.
Oh- another nearby option is the Whole Foods. They were not inexpensive, but it is a very diverse grocery store. In the before times, they had all kinds of options like a real pizza oven, full bakery, barista, and many hot bar soups. But also great selection of yogurts, cheeses, fresh fruit, healthy packaged snacks. That same plaza has - or had - a few other decent quick serve options.
In Citywalk we also like Breadbox for an inexpensive option. Tomato Mozarella is great!, Cold Turkey is good. The melts tend to be pretty greasy though. Ironically, the fries are good. There are also a few other fast food options. The rest aren't great, but they are inexpensive (like burger King).
Skip the Simpson's eateries, except do look at the mural of all the characters.
Oh- big thing to know about Universal is the lockers on the big rides. If you an go bagless, so much the better! Do NOT bring a huge backpack! If you must carry stuff, go light/minimal! Lockers are free (up to a certain size), but they take time. Also, don't bother with the refillable mug, or you'll have to deal with putting it in lockers all day. If you do get AP's, in the before times, Universal had an AP lounge, It didn't have much but water and a place to sit. Universal also used to have a secret lounge for anyone that buys tickets with an American Express Card. Both were only open certain hours, but free water/chips was free water/chips, and a place to sit. AE lounge is by Shrek meet n Greet. AP lounge is by the Horror Show and a neat gift shop that sells (or did) sell props. OH- also do check out the artist shop if it is open, it was by Fire-Eater's grille.
