Hi, some thrill rides I won't go on but most of those are the really huge rollercoasters in other (non disney) parks. I don't like the type of rollercoasters that goes up a 200 foot hill with an almost straight down drop (those freak me out). However, almost none at the Disney parks freak me out with exception of ToT (but I still try to ride this one at least once a trip).
You mentioned that you would like to try Maelstrom, Kali River Rapids and Dinosaur. Maelstrom is extremely similar to PoC. You load into a viking boat (same size as PoC) you go through caverns and have a very small fall to go over (this doesn't have any extreme dip) and doesn't make my stomach go into my throat.
Kali RR is a somewhat bumpy water ride as your supposed to feel like your riding on one of those white water rivers. Sometimes you will spin more than other times you ride. If the spinnning makes you quesy, you may want to rethink (depending on the CM, they can start the raft spinning when it leaves the dock - sometimes they do sometimes they don't). The ride is going to do a certain amount of spinning just because it is made to do that as it is bouncing off the walls of the river. I don't find that it makes me quesy, but my mom always gets off feeling quesy and will only ride it once per trip. There is one drop (which isn't large andthe drop isn't severe) but if the side of the raft your sitting in is the first to hit the water at the bottom, your going to be the very wet one getting off the ride. My last ride on it in Nov proved this last statement. I even had on my rain parka but came off with my shorts being completely wet. Oh well part of the fun.
Dinosaur. I don't get sick on this one either but I do sometimes feel a little quesy when I get off. This isn't a rollercoaster but the ride vehicle does ride on a sort of rollercoaster track. I usually describe this as a motion similator ride on a rollercoaster track. There is a small dip but your stomach won't end up in your throat as it is a gradual dip. Motion similars can make me quesy. Your ride is in the dark and when you do see things there very loud and suddenly bright. The loud parts get to me more than the dinosaurs trying to get at the vehicle. By the way, there is always a lovely photograph taken during the loudest part of this ride when the dino is trying to eat you. The photo always comes out the same for me, my eyes are closed and I am trying to hold my ears in from the loud screaming dino. I do like to ride this ride every trip and would encourage you to do it at least once.
As for the roller coasters, I ride them all because I consider them to be tame. RNRC doesn't have any dips but is very fast, goes upside down with a few inversions but is over quickly. The only thing scary is how fast it takes off as it will take your breath away for a few seconds.
I completely agree with an above poster in that if you can handle the kiddy coster, Goofy's Barnstormer, then you can ride BTMRR all the times you want. BTMRR has 3 hill climbs but none of them end up in a straight down fall. They all end up in corkscrew turns which always make me giggle and you get a few bunny hops (very very small up and down dips of about 3 feet each up and down) thrown in at the very end. The ride is fast and does go something like 43 or 45mph but it really doesn't feel that fast. If Disney ever would have one of those rollercoaster challenges on BTMRR, I think I could ride it straight for several months.
Space Mountain. This ride intimidates people because it is pitch black in there (there are times when you can make out theoutline of the track your riding on). This rollercoaster actually goes about 40 mph (yes slower than BTMRR but you can't tell when your in the dark). This ride does not turn upside down but has two dips (not tall or dipped at a steep angle). Actually I think the bigger of the two dips is probably only about a 50 foot drop (if that) and the drop isn't steep but you mostly have very tight corkscrew type turns. The ride is meant to give you the illusion that your out in space and for a brief second or two when you go up the first hill you coast and it does feel like your floating then you turn into the first set of corkscrews. I love this ride and probably rode it no less than 20 times my last vacation. Don't get intimidated by the darkness and what you can't see. It's fun and is over within a minute.
Lastly, MS this is a great ride unless your like me and get quesy from the spinning.
I say take your time, try them and remind yourself during riding them to breath normally and that will despell some of the anxiety about the ride. Most of Disney's rides were truly not meant to be extreme thrill rides, but were to allow children a different experience without scaring them or there parents to death.
