
You know your kids. And they are older than my guy. But my guy wasn't the biggest fan of Matterhorn b/c it's so rattly and it throws you around a bit. Then again, he REFUSES to go on BTMRR, and honestly, I'm fine with that. Sure I go on it, but it's not my fave.
If the kids don't mind the dark, and if they like Star Wars type things (it's not star wars, but it's close enough to a kid, or at least to me and my brother!), I might go for Space Mountain! But if they don't like the dark, that's a no go.
And honestly, IMO the smoothest, silkiest coaster is Screamin'. The take-off is rough, I won't lie, but then I have a tendency towards asthma so I don't like the chest-pressing feeling it gives. But after the take-off, it's a great coaster, and I'll go on a million loops rather than the "is my head going to be lopped off" feeling that Big Thunder gives me! (the answer to that question is NO, especially b/c I'm sitting and I'm only 5'3", LOL) For me, loops are a breeze, and actually feel better than drops.
But you could always insist on starting off with the Go Gadget coaster in ToonTown, it's maybe a minute long; sort of a starter coaster. You could just say no coasters for the first day, let the kids see the things they can see, so you are SURE you know what they are getting into. And sure you know THEY know.
Indy of course isn't a coaster, but it's a crazy, rocky, bumpy ride. Many people really brace themselves during the ride, but I do better when I let myself be loosey goosey on it. I plant my feet, put my hands on my lap, sit up (rather than hunching), and just go with the ride. I always feel very good, spinally, after the ride.
I worry about my son being scared on rides...and because of that I've been OK with him not wanting to go on BTMRR and Space...so I get the paranoia, but they're physically big enough and they are mentally wanting to go, so really try to figure out a strategy that lets you be comfy with them having the fun they want to have.
Someone mentioned TOT, great ride! My guy loved the ups and downs (he went on his 4th birthday) but was afraid of the effect even before the drops start, where it seems you disappear. He hated that! But your guys are 2 years older than he was, and I'm sure that won't bug them unless they are very sensitive (which is FINE if they are!!!).
One last thing, youtube has videos from all the rides I've looked for. Very helpful. In case they want to see, or if you want to watch it to relax yourself a bit more.
