When I design a new virtualization infrastructure, I consider all those points :
- Have one vSwitch for management purposes (Management, VMotion) : it can be a distributed vSwitch as it depends on your wishes/believes -> Some do not want to have management on dvSwitches, some prefers ... It's your own business to decide. I prefer vSwitch as it's easier to troubleshoot in case of damages at 3:00 AM 
- Have one VMkernel port for Management Network (at least)
- Have one VMkernel port for VMotion
- They can be both on the same vSwitch and you should have 2 vmnics. Some use to configure each VMkernel on a different "active" vmnic using the other one as "standby" (crossing the configuration on those VMkernel ports)
- Separate using VLAN VMotion traffic and Management traffic. Configure the 2 vmnic with VLAN trunking on the pSwitches
- With older version of vSphere, I used to have 2 separate VMkernel for Management on 2 differents VLAN, to avoid any misconfiguration by the Network team. But, I think this is not usefull anymore as vSphere 5 introduced Datastore Heartbeat to prevent Cluster from shutting down VM (for HA) is case of Management network unavailability (vSphere host considering itself as isolated and applying the defined cluster policy).
- Have another vSwitch for VM Network. Ideally, Distributed vSwtiches are used to have the benefits of all the latest technologies : depends on your licensing level
- Have one (d)vSwitch with its own vmnic for iSCSI
Hope it helps.
Regards.