I'm a huge roller coaster and thrill ride fan, but for the longest time I never even dared to go near ToT because I don't like free-fall rides, like the green Dominator at Dorney Park - I just refuse to go on it becuse it drops riders 200 feet in open air, you're back is towards the tower and you're arms and feet dangle.
Anyway, I love RnRC. And the last time I was there, like 3 weeks ago

, I finally got the guts to just go on Tot. Personally, yes the building is cool and the effects are great, but I don't think that it's the ride that everyone thinks it is. Maybe I'm missing something. IMHO I think that RnRC is the best ride in WDW.
I think that there might be parts of the ride that may scare your daughter, especially while you're actually in the elevator and strapped in. The effects are incredible, but even I was a little creeped out.
I'd say to see how she hands Big Thunder and maybe even Splash. Also Star Tours in MGM. But as for which one she should go on first, I'd say RnRC because of the safety harnesses - I'm sure she'd feel a lot more safe because the harness comes down over your shoulders and she has something right in front of her to hold on to, not on the sides like ToT or nothing if you're in the middle seats. And once the initial take-off is over it's not too fast. If she can handle RnRC then she can definately handle Space even though she'd sit alone and ToT.