I like your choice of scan but I I'd like to offer some tips that might help make your wallpapers look more stylish and interesting:
I think I've already mentioned the lineart in one of your previous wallpapers but your walls would definitely benefit from a more dynamic lineart - having just one line width for everything makes everything look too static and boring so I would recommend using different programs that can enable you to use Vector tools like Photoshop or Illustrator's Pen Tool. SAI is more painting oriented, not for vectoring so it doesn't exactly have the necessary tools for good vectoring.
Your vectors/characters also need more details like shading and lighting. Also, don't try to blur the shadows/colors so much, it makes everything lose a lot of detail and look out of focus. I see a lot of people blur their shading lately which is not something that works on everything, especially not things like hard, solid surfaces. Since you're using SAI, you can make use of the Water tool to make things look more smooth and blended.
And last, while using stock photos for backgrounds is not forbidden, it's also not advisable to use them with vectored/animated looking characters because then they clash too much. It takes a lot of blending and modification to make those two things look as if they really are a part of one picture. So, as a rule, if you have an anime/manga character that's either extracted or vectored, it would be good to vector/paint your backgrounds as well or browse some scenic scans here from various anime/manga and use them for background.
Overall, you're on a good way so make use of the tools the programs offer you and keep practicing. :)
