I don't know how familiar you are with Georgette Heyer. Basically, she wrote A LOT and she even invented a whole new genre: Regency Romance. 
 The implications the Romance genre carried back then (this is one of her latest works, she mostly wrote during the first half of the 20th century) were not the same as now: this is not a bodice ripper, with lots of sex and cliches and basically only 2 main characters, set in the past and romanticizing it. It's more like if it were written during Regency. Only not. 
 The premise of the book is nothing special: Sophy, a very independent and practical girl, is left with her aunt and cousins to spend some months while her father arranges some business elsewhere. The plan is to find a husband whilst she stays there in London--but as I said, she's not a romantic, she's a pragmatist, so she is not looking for love, but for a suitable companion. 
 This plot is actually quite secondary to the book, though. Because Sophy is a force of nature, and everybody loves her and goes to her for help--despite being new in town. So basically, the whole book is Sophy trying to fix the messes her cousins start. There's the angelical girl in love with a poet, the middle child addicted to gamble, the little ones, and the serious and grumpy Charles, who acts as a father to his own siblings. 
 It's really really fun to read. It's not completely original, but not quite predictable either. All the characters are very different, and although Sophy can be sometimes a little bit annoying, she is not judgemental at all. There's love for all the characters and all the pairings (there are many). 
 I suppose this is a "girls' book", but don't read it hoping it'll be a romance. It is not. It's a very modern and feminist book, without being, you know, completely out of place.