OK, so I am guessing you haven't been to the parks before? Or at least that's how I am taking it
Of course, the castle (in Islands or IoA) best spot is on the bridge between Hogsmeade and Jurassic Park. In line for Hippogryph, you can get a shot with Hagrid's Hut behind you (you can carry all items on that ride) Probably a lot in the line for the castle ride (Forbidden Journey), but this is a locker ride for larger items, so you'd have to be able to fit your camera or phone into a pocket or hip bag.
Diagon Alley (Studios) there are SO MANY, everywhere you turn is crammed with signs, advertisements, little Easter eggs, etc. Hagrid's Motorbike is a fun one, the prop is in Diagon, and there are many windows and displays. I've been more times than I can count, and I am still finding little extra things.
In London (just outside of Diagon in Studios) there is the Knight Bus (if you go to the back, you can climb on the steps and have a picture there, the phone booth for dialling the Ministry and Kreature is there in Sirius' house.
In the NY area of Studios, straight back from the entrance, all the way to the end, is a green subway "exit," it looks just like the one in Fantastic Beasts, when Kowalski steps into the rain