Temperature plays a crucial role in the life of your wines. If you do not plan on cellaring your wine, consider a refrigerated system from Sub-Zero. This will also take care of humidity, which should be moderate.
Though it may be tempting to set up your wine bar near a lovely picture window, think again. Darkness is key for preserving and storing wines. Again, if you're cellaring your wines elsewhere, not a problem. But if you are storing your wines where you're drinking them, go for the shaded spaces.
Consider a spacious racking system so that you needn't disturb other bottles when getting at a particular choice.