Home improvement, take 2

I've been in my new place a couple of months now, and the walls are still ugly and bare. My art and mirrors and the like are still languishing in a closet because I don't want to hang them until I've painted. And I haven't painted a damn thing, for I'm crippled with indecision. So, I'm asking you guys again for your input. I figured it might be easier with some photos that include my belongings. So, here goes (click on the photos to enlarge them).

The entrance to casa de Grammarian:

Now that I have a real and most delightful stereo (thank you again, generous one), I intend to get an entertainment center of some sort, but you get the idea:

View from upstairs:

Where I release aggression:

Sofa and fireplace:

The stairs:

The bedroom (you may have noticed I like gray and black):

View of the shower from the bedroom (bow-chicka-wow):

The creepy carpeted and many-mirrored bathroom:

Downstairs bathroom with hideous wallpaper:

And last, the kitchen of blue despair:

So, what do you think? Gray walls throughout? Something more colorful? I'm seriously at a loss when it comes to stuff like this, so please, please help me.