Visio is a de facto standard for IT. Personally, I find the library images overkill and like a simple clean icon.
Considerations - to draw an existing network you want a tool with autodiscovery. To build an inventory of the devices usable with other applications, look to an autocad type system with a database module. To generate work orders based on a design, look for a tool that outputs both drawings and part lists, and has rack drawing templates. A cable inventory module is also a goodidea for work orders.
If you want a tool that will do an automated design for you, I suggest you use a VAR (value added reseller). They will probably create one in Visio, but will have an engineer determine addressing, collission domains, etc. You might want to get a response from several, since there are varying approaches and not all network engineers are adept at looking beyond the basis request.