Agree with what a lot of others said here.
Forbidden Journey is a thrilling dark ride with lots of motion, but there are not drops or launches or anything. As mentioned though it can cause some motion sickness for many so might try to do it later in the day, but definitely with checking out for fans of the series. Most of the motion sickness for people seems to come from the screen based portions versus the physical sets too so if you have to can close your eyes during those, just peek to see if it's done for when to reopen. [Not really a ride to compare to honestly. You can see pictures if you want to get a better idea online without watching a video. Or for an idea of the vehicles/system can search robocoaster]
Gringotts gets classified by a roller coaster by many but really it's more of a dark ride with some roller coaster elements. Id' say 90% of the ride is a dark ride with 3D screens, but it does have one small drop (estimated at around 30' but no exact details have been given - for comparison Splash's big drop is 50') at the start and a launch at the end that mainly goes uphill to get you back to the starting level. Neither are too intense and are very short segments that only last a few seconds each. [Overall it's very Rataouille-esque with just a couple very small coaster elements added]
Hogwarts Express is a train with video screen windows. Definitely recommend it, and do know that the experience is different each direction so do ride it both ways (Kings Cross to Hogsmeade, and vice versa). Also keep in mind, you said you did not plan to ride any with them, but this is more of a transportation system then a typical ride. You board the train in one park and get off it in a different park so you would probably need to ride with them. If you are not a ride person just know it is a very slow moving system that is a themed experience to move you from one land to another more so than a standard ride. Honestly biggest comparison outside the train would even be the parking lot trams at Disney. There aren't even restrains or seatbelts you just sit on cushioned benches.
The other two rides are coasters.
Flight of the Hippogriff is a small kids/family coaster. It's sort of Barnstormer level. You can see the entire thing as it is all open in a small footprint so can decide for yourself. It has a great Hippogriff animatronic at the start, but not really missing much if you skip it.
Hagrid's is a large family coaster with multiple launches and a couple small surprises. However, there are no real big drops on it. There is just one spot that does peak up higher but if you sit to the back of the train you will no go very high at that point. The start of the queue line gives a view of a portion of the ride so you can check it out and see if it's something you all think you could handle. It is a lot of fun and not too intense, and very smooth, but if you all hate coasters it might not be as enjoyable.
