In the seemingly never ending battle of organization in our new house, the garage is one place I've been working hard on! I had the bikes hung up on the studs, but that wasted some space. I screwed a 2" x 4" x 10' to the ceiling and then was able to put bikes 12" apart. This way the bike spacing is nice and tight but they're not on top of each other. Here it is with no bikes up:
The new style
My 29er mountain bike is noticeably longer than my other bikes so it got it's own hook at a longer wheelbase:
For the longer bikes
That's about it, now everything can be hung up, including the dog trailer. It looks kind of like a buffet of bicycles, which I LOVE SEEING.
Hanging them like this is both efficient and safe for the bikes. Best part is that with them hung by both wheels I can walk under without throttling my gourd.