Consider that your wireless requirements may also involve a hybrid of security methods. For example, you may wish to allow restricted access for some people (i.e., giving guests limited Internet access), yet allow unrestricted access to employees who need to attach to corporate networks.
Consider the question of who will need to access what data and from where they will need to access it. For example, you may wish to lock down certain, highly sensitive applications, to be accessed only from specific locations. Do your wireless users need access to financial accounting data? Wireless security should be a logical extension to your existing wired security requirements.