Hi,
I think it will be better for you to create a specific VS:port by service.
you can have more flexibility in terms of monitoring and maintenance. because if you pool all services it will be difficult for you to define a reliable monitor.
if you have only on VS if on monitor goes down it will affect the service if you set "Availability Requirement" monitor to All.
And if you want to opere a maintenance only on DNS you will impact LDAP/AD service.
I hope it was clear.if you want more details let me know. but that's my point of view. everything depends on your requirements in terms of flexibility and monitoring and also evolution...