Not trying to be unhelpful, but I think every kid is different, even at different ages. Different kids will think characters are scary, exciting, fun, uncool, even at the same age. The characters with real faces who talk can be very different from the fully costumed characters. Here are a few anecdotes, from my two daughters at various ages:
- At 1 year old, one daughter was screaming in sheer terror when Mickey started walking her general direction at Chef Mickey's. We had to take her out to get her to stop.
- At 3 years old, one daughter had a great time meeting princesses. She didn't want to have anything to do with Mickey and the gang at all.
- At 4 years old, one daughter was somewhat nervous around all of the characters. She got over it enough to talk to her favorite princess at the time, but didn't enjoy meeting them. Meeting Mickey at a meal was also uncomfortable, but she got excited about Donald (since her dad was excited) and Goofy actually made her laugh a bit.
- At 7 years old, one daughter was OK with characters, but not especially excited.
- At 9 years old, one daughter seemed to really like all the characters, but more in the sense of trying to get her much younger sister to interact with them. Had it just been her, she would have easily had a take-it-or-leave-it attitude. I think having the younger sibling along gave her the freedom to enjoy it more on her own.
For all of those, we saw other kids of the same age with very different reactions from our daughters'. You know your own kids better than any of us. For 7-to-10 year olds, my guess is that they might act as though it's not-so-cool to do, but yet still enjoy it if they give it a chance. Same thing could be true for some rides (though the "not cool" probably comes as they get older). At that age, though, you could probably just ask them - if they seem interested in meeting characters, then a meal might be a good option. If they seem really negative, then skip it.