At this point in time, and I'm pretty old, the only rides I have significant nausea/motion sickness issues with are inverted coasters and 'very fast' circling flat rides, like Bayern Curve. Until I hit 40 I didn't have issues with any of those. Curiously though, since I had cataract surgery two years ago, which gave me non corrective medium/long distance sharp vision for the first time in my life, I no longer get even a tiny bit of motion sickness on coasters like Everest, medium speed flat rides, and Simpson type simulators. I've usually read that inner ear issues associated with aging cause some motion sickness, but with me it ended up being vision oriented. Now I can ride stuff that I used to get a bit , though not horrible, nausea/motion sickness on, without any issues.