Stay at the cheapest deluxe hotel. One night = two days of express passes and it’s worth it. We were just there the week before Christmas and still waited 30 minutes one way for the Hogwarts Express, same with Flight of the Hippogriff when it went down to one coaster vehicle.
FJ is bad for nausea. I can ride anything at Disney and adore FoP, but I only will do FJ once per trip to appease my eldest. Gringotts is much better, more in sync.
Hagrid’s is worth the hassle of early entry. It’s my favorite coaster second only to Guardians. Hit it first, then hippogriff, then FJ in that order. Take the train over to Diagon Alley. Ollivanders then Gringotts and you’ll have knocked out most of HP before the crowds really arrive. Reward yourself with a strawberry and peanut butter ice cream from Floreans while you peruse the shops and wand spots in Diagon and Knockturn Alley. Adopt a Pygmy puff at Weasley’s. Lunch at Leaky Cauldron, then go through the bricks to visit the Knight Bus, see who’s peeking out the curtains at 12 Grimauld Place, and don’t forget to dial the ministry from the phone booth.
My mom is very prone to motion sickness. Her favorite rides at UO are the Hogwarts Express and Men In Black, and she enjoys the Seuss trolley too.
Have a great trip!