Nicole to respond to your post, I've never read any of the YaYa books, but after looking at the cover's I am intrigued by them. The background colors are vibrant and bring life to the pictures. The use of the colors are clean and they compliment each other. The spacing make them clean and easy to read. Also the images are strong and convey the point of girls having fun. I agree that they do also have a nostalgic feel to them. I think the dark type treatment works as well on the bright backgrounds.
These nostalgic feel reminds me of the a series of books I use to read as a child, Goosebumps. For me a cover is a selling point of if I want to read a book or not, when trying to find new material to read. I think R.L Stine utulized these elements in his covers from the color to the actual picture to give you a description of the story.
