When we decided my son was old enough, we moved him across the hall from the nursery to his "big boy room". This room was another series of stripping wallpaper, removing carpet, and floor refinishing. I found a ufo graphic online that I liked, and sketched it out on the wall with chalk, then filled it in with grey paint. The alien and the robot are outlines of an Uglydoll and a robot softie that my son sleeps with. He also has a little ghost/goblin named "Blah!" that he asked me to paint, so I plan to add that and another, smaller ufo.
The rocker was a vintage find from my mother, and I plan to rewire the old metal Saturn lamp. We'll swap out the crib for a farmhouse-style twin bed soon, but the toddler rail made the transition to the new room easier for my son. And it's not pictured, but I inherited from a friend a 1960's "flying saucer" glass pendant lamp and hard-wired it where there was a ceiling fixture. Kids' rooms are so much fun to do, and they're the only rooms in the house where I don't mind having a bit of a theme.