Ro is five. I'm mostly concerned because she is kind of a sensitive kid, and tends to empathize a lot with the characters. She's been very reluctant to watch anything that might have "scary" parts, meaning basically any conflict, tension, danger, etc. Lately, the thing we have to keep explaining is that all movies are going to have situations where characters are in danger, in conflict or facing some kind of difficulty, and there is usually going to be a bad guy, because that is what drives the story.
She's moved up to more action-oriented kids' movies, and loved How to Train Your Dragon, which is why I think she might be ready to try something more mature. That, and she's reading well enough to start asking questions about the movie posters on the walls. She still needs to get a handle on the idea of actors playing parts, but she has a pretty good grasp of make-believe. She's watched parts of Godzilla movies since she was about 3, and can tell you it's people in rubber suits stomping on tiny buildings.
The main thing is that I want to show her something she can understand and follow without being too distracted by concern for the characters or questions about details that don't relate to the story. Mind you, when I saw Star Wars at six years old, I don't think I knew what the hell was going on, but it was fun to watch.
Okay, then I reiterate my suggestion of Harryhausen films - IT CAME FROM BENEATH THE SEA being a good one. Also, DINOSAURUS! was pretty good (complete with a kid riding a dinosaur), but she may feel sorry for the dino's that get killed.
I'm wondering how much The Uncanny Valley plays into her empathy - if it's "off" enough, she's okay? My daughter, when very young, had a VERY hard time with things that were 'almost' real, but not quite (angel figurines in a store that had no faces painted on them sent her into screaming fits) - but as you say, something like Godzilla was okey-dokey.
My son is 5, and we had an absolute ball watching ASTRO ZOMBIES with him...all on his own, he gave a very MST3K-esque riff track to it the whole time. It was hilarious. The movie was just so goofy even a 5 year old could tell it, and this from one who wants to believe everything is 'real.'
I guess the common thread in what I'm saying is stick to stuff that the fx are 'easy' to explain away as 'make-believe.' I love Harryhausen's work and am not trying to downplay his art, but a giant octopus that does some of what that one does is pretty easy to say, "see, it's not real...a man made it LOOK real with a camera trick."
You could introduce this idea, too (if you have not done already) with some digital stills using forced perception and other trick photography, and let her do it to. Exploring how the movies were made and the fx were done is a BIG part of what I personally enjoy about b-movies, and for me that started when I was about your daughter's age.
Also, if you feel more ambitious, one could do some photoshop stuff (put her in front of the Taj Mahal or some such), etc.
Good luck and have fun with it...the visual art of special effects is yet another way a child can explore the world.
