I JUST GAVE MY KIDS A TRIP TO UNIVERSAL/IOA, SW,DC FOR XMAS AND I TOLD THEM THAT UNIVERSAL WAS SOME FUN UPSIDE DOWN COASTERS AND THEY SAID WILL WE GET SICK? I KNOW IT DEPENDS ON THE PERSON BUT ARE MOST OF THEM UPSIDE DOWN AND DO THEY MAKE YOU SICK?
I don't know how old your children are, but there is a "kiddie coaster" in each park too. The Hulk and Dueling Dragons certainly twist and turn, but it depends on each person. I know people who get sick on spinning rides who are fine on the coasters. The are GREAT!
I get motion sick easily but managed fine. Just make sure anyone who has problems paces themselves and doesn't do the motion simulators right after each other or right after the coasters. And beware the Back to the future ride. That is the only one that killed me. Everything else will be fine as long as you don't jump from one to another to quickly.
There are really only 3 roller coasters in IOA and one is a kiddie coaster. There is one kiddie coaster in Universal. I agree with the others, I wouldn't go on the big ones after a big meal but mostly they are very SMOOOOTH.
I get HORRENDOUSLY sick and dizzy on some rides but NEVER got sick on the coasters at either park. The only ride that even gets me slightly dizzy is Back to the Future at the Studios.