Diana = Serena 
 Elizabeth = Vanessa 
 Will = Dan 
 Penelope = Blair. 
 Henry = Nate's looks and Chuck's morals lol 
 ....I'm sure you get the idea.... 
 This series is entire fluff. And yet, it's mildly entertaining, secretly amusing, soap opera-esque intriguing fluff. 
 I just picked up the third book this afternoon, and will probably finish out the quartet out of pure, lazy curiosity.