It really depends on what you are trying to accomplish. If you need portability and very constant change, wireless may be a better option. Probably a mix of the 2 would be more advantageous. We offer a product to some of our clients where we connect their remote offices to their main office wired system over a wireless link. It provides that flexibility. This way, they can move a Job trailer and be reconnected in a few hours and they get their phone, fax, and internet on the same connection.
You need to figure out why you want wireless. Is it just because it is the in thing? that is not a good reason to abandon the wired system. And like ButtonIt said, wired systems are extremely reliable which equates to reduce maintenance costs.
Keep in mind also that wireless products are flooding the market at 2.4 GHZ and interference and "hot spotting" will be more and more of a problem.
good luck...