Five Little Peppers! I ate that kind of plucky economical treacliness up with a spoon when I was a kid. There were a bunch more books after the first one, but I never read them because I wasn't interested in rich kids being treacly.

(The Boxcar Children did the same thing decades later - the plucky runaways were snapped up by their fabulously wealthy grandfather at the end of the first book, and all the books after had them being fabulously wealthy to an annoying degree. I wanted more cozy old-timey economies and fewer helicopter excursions).

Hah, My Brilliant Career sounds magical. One more for the neverending rec list!