This one's definitely for Claudia, who from the very beginning of From the Mixed-Up Files of Mrs. Basil E. Frankweiler is bored to death with her suburban, childhood life. We get the sense that Claudia isn't even happy when things are perfect—she wants to run away, after all. She's not happy with her family, school, or even herself, so she goes on this quest where she's not really sure what she's seeking out. It's kind of like playing chess without knowing the rules (except with higher stakes). In the end, though, Claudia finds the excitement and adventure that she needs to go back home happily—instead of kicking and screaming.
Claudia experiences dissatisfaction because she is such a perfectionist and overachiever in her everyday life; things come too easily and she gets bored.
Even with all her expensive and nice things, Mrs. Frankweiler is still dissatisfied with her life. That's why she understands Claudia's reasoning so well.