Vlan design for guest vms in virtual desktop environment

Hi

I am planning to migrate my physical desktops to virtual desktops.Currently we have different vlans in different floors of our office as well as branch offices .Some users have client server applications and hence lot of them in different departments have point to point firewall rules open and in place..we are planning to group images based on departments and applications used by them..how should I be designing virtual desktop vlans..I think it's a dirty practice to maintain one to one firewall rules as now to cater specificequirements..what are best practices in virtual desktop world