I don't like/can't really handle Star Tours because of the 3D aspect - THAT makes me sick, because the glasses never fit and it plays with my vision too much.
I really, really, really enjoy the thrill of MS: Orange. It always freaks me out because before we load because I *think* it's going to make me sick, but in the end ... I get SUCH a rush! We went two years ago with a buddy who LOVES space and his childhood dream was to be an astronaut. Even after three or four times riding it, we'd be waiting outside the capsule, he'd get all pumped up (and slightly excited-nervous) to go in the capsule, because it felt so real to him. Like he was finally doing something he'd always dreamed about!
I've never felt the spinning aspect - but really only the rumbling of liftoff (and what I always think are nerves in my stomach) and then the weightlessness, and then the feel of awesomeness.
I feel like the key (for me!) is to keep my back straight and my head basically plastered to the back of my seat, and keep my eyes open and focused, essentially, on the center or what the ride establishes as the horizon. If I've ever lost it, it's when I've closed my eyes, but even then - I've never felt the spinning. DO NOT CLOSE YOUR EYES. There are enough things visually to focus on that will fool your brain into thinking you're really in space and not spinning. Looks around at the screens other than your viewfinder, or at your fellow "team mates". DO NOT CLOSE YOUR EYES. Just focus on pressing your button when you're called on!
We've done it a handful of times and it's only made my husband feel funky once - he hadn't had breakfast yet, but had finished off at least three cups of coffee, so I'm sure that played a factor.
Honestly, I feel like it's pretty amazing and breathtaking in the experience of going into space. It's easily the closest I'll ever get to doing that!