Many people who have the 4" granite lip opt for a painted back splash-same as walls. That's what I'd do.

For the wall color: I'd choose a paint the same tone as the floor

For an accent color in the kitchen, I'd buy art to repeat the blue of the counters & use maple frames (maybe small accents of gold & green as color accent, too...but mainly blue).

I agree with olldj22 - since you have the 4" splash already, just paint same as wall paint. But, I do think you could be rather bold with paint color. I really like the first photo posted by olldj22.

I'm not sure if it's possible or not but just take off the granite backsplash. And your right a backsplash in there would really improve the space also have you thought about under cab lights they are really inexpensive especially if you or a friend are handy and can DIY. I do agree putting in a new glass (or tile) backsplash while the granite 4" backsplash is there isn't gonna work. And painting isn't really gonna do anything for the space in my opinion. So if you can take off the granite backsplash I would recommend putting a very neutral glass backsplash because with maple cabinets and blue granite it's gonna be hard to find a color that will match but hey it's not impossible. If it was me I would bring home samples from a store and hold them up in your light and see what matches don't buy it before seeing it in your own home. I think that clear glass might look the best here are a few examples. Hope that helps!

Despite of the "now" white subway / glass pattern tiles that are now in trend, they are notoriously annoying , a.k.a. a real labor of love, to maintain them clean, looking up notch. Unless you are selling, just think of having to clean all these grooves and grouts in between those small little tiles. I have those unfunctional 4" backsplash and 1/2 wall tiled backsplash in our house. Food and splashes always go everywhere onto the untiled wall area, which is totally annoying when the paint smudge off when you are trying to get those dirt off the wall even with mild detergent. I cannot wait to change them up to either large granite/ marble / temperature-resistant quartz FULL-Wall backsplashes.