The only thing I don't like is how the line art for the circle goes right across the main focus of the image. If you scrubbed that part out it would stop interfering with your character art, and would give a much cleaner appearance, overall.
Besides that, I think you've made some great pose choices here, and it works very well as an O.C. compilation. The color scheme is quite nice as well, with all of its contrasting blues and pinks. The subtle drop shadow also looks good. Lots of little touches here and there, and I really like how you didn't just rely on black for your line work.
Maybe you should consider putting Mug on an actual mug, and other things besides. But first, those circle outlines really should be relegated to the background, like in the one where she's sleeping.