Bicycle rack designs are awfully frustrating. The world is awash in racks that are nearly impossible to actually lock your bike to. I don't even understand why these things are manufactured. Some will hold your front wheel, but you can't get your frame close enough to use your theft-resistant U-lock, while leaving most of the bicycle unsupported so it falls over and gets damaged... Some racks are okay for a skinny racing-style bicycle but won't fit a commuter bicycle with racks, baskets, and fenders. Other racks have artistic features that make them hard to use.
Sevananda Natural Food Store recently spent money to have their parking lot repaved, but failed to upgrade their rusty old bike rack. This large rack really only provides two parking spaces, because the center section does not provide slots wide enough to slide a bicycle into, plus the crossbars are high enough to hit the bottom of your frame or fender. I'm not even positive that it is a rack, and not some sort of repurposed barrier. Guess I should have gone to the members' meeting to discuss priorities...
Georgia Tech invested in these double-T shaped racks. According to a diagram on the rack, you are supposed to hang your frame from it where the top tube meets the seat tube. But many of us have sloped or curved top tubes that don't fit over these things. Plus, a fully-equipped bicycle can be too heavy to lift that high, or put too much stress on that part of the frame. People use them creatively instead.
The best rack is always a staple rack, the ones that look like an upside-down U. It supports the frame and provides a variety of locking points, even if someone is parked on the other side. When you need more parking, you just install more of them. You can scatter them throughout a shopping district or provide long rows of them at major destinations. The renovated (and totally awesome!) pool at Piedmont Park got it right. They're going to need it - this array of racks was already half full when I visited the other day, and many people don't even know that the pool has reopened.