I can't do "spinny" rides at all, or even tackle the ones that don't spin, but are jerky in motion (i.e. Dinosaur at AK, Star Tours, etc.). As the Carsick Queen, I can get sick driving myself five minutes to the mall and once even got motion sick on Peter Pan's Flight because of the way the ship was moving back and forth (pathetic, I know). I got incredibly motion sick from the driving simulators at the end of Test Track. I was so sick, it ruined the rest of my night and I was out of commisson until the next morning.
However, I didn't feel the least bit sick on Soarin'. Granted, I rode it first thing in the morning, before I had eaten anything, just in case I'd misjudged the ride and would end up sick. A couple things that help with Soarin' is that it's very smooth and the rush of air against your face is invigorating. It kept me from feeling closed up in a stuffy place, plus I was so distracted with the scenery and smells, I didn't have time to think, "I hope I don't get nauseous."
As with any ride that I normally love (ToT, Space Mtn, R&R Coaster), I will get queasy on those if I ride them more than twice in a row. Two back-to-back rides is my threshold. It would probably be the same for Soarin', but I'd definitely try it once, even if you have to take 1/2 a non-drowsy Dramamine an hour or so ahead of time to make you feel more comfortable. It's a ride NOT to be missed!!
Jodi