Sites for companies with offices in just one state belong in the appropriate subcategory of the state, linked from here.
If your company has a single office, your site may be listed once within the state your office is located in. By default, hosting services will be listed at the state level, unless there is a clear focus on providing services to a smaller area, in which case the service may be listed at that lower level (locality, municipality or region).
Please note that in general companies are entitled to only one listing under Regional/Oceania/Australia so submit your site to the most appropriate single subcategory for the range of services you offer.