Keep in mind that when you put devices on VLANs you have to route between those VLANs so this can add some processing overhead that is not there in a simple flat switched network. So, if there are devices on VLANx that frequently talk to VLANy then there will be overhead on the routing device between those VLANs. There are some VLAN vulnerabilities out there so you should take some time to understand the risks for your environment. Unless your network is large, carrying lots of traffic or there is a security need, I would stay away from VLANs for the most part. Another time that you would need to implement VLAN’s would be to support IP telephony. This will permit QOS & COS to be placed on the traffic. See my blogs on some VOIP/IPT considerations.
Most switches today can handle a lot of load without VLANs – you should see what the traffic loads & traffic types are on your network to see if you get any return on a redesign using VLANs.