Hi.
Just to share my own experience with running VMWare Workstation 10 for a little over one month-- disk usage with it is very high. You will see benefits from having a fast storage device for your VMs. While SSD would be great for performance, disk usage space for a VM may be very high depending on your configuration. For my own desktop workstation, I did not choose SSD for this very reason. SSD storage space is quite limited. While having large space with SSD is possible, the cost of it will be very very high.
What I did was choose two hard drives -- 1TB 7200RPM that my Windows 7 OS is installed on (boot drive); 2TB 7200RPM that all my VMs exist on.
I currently have five different VMs on my 2TB drive. Just to give you an idea of storage space consumed by all:
FreeBSD 9.1 consumes 9.88GB
Windows XP 32-bit consumes 25.1GB (note that I uninstalled some components that I do not use that reduced this size)
Windows 8.1 64-bit consumes 50.9GB (nothing removed at all)
Windows Server 2008R2 consumes 11.2GB (this is a very thin customized install of the core OS and required components)
Windows Server 2008R2 consumes 43.6GB (larger install for this second instance)
For the memory that you allocate for each VM, VMWare will create a file on disk of this size. For my Windows 8.1 VM, I allocated 24GB of memory. VMWare created a vmem file that is 25,165,824 KB in size. It will do the same for every VM you create. This is why fast disk access will benefit you.
I also have shared storage that my VMs use through my NAS. It is accessible through the VMs, but I have to enter network credentials when using my WIndows 8.1 VM. Microsoft seems to have changed the way logons work with Windows 8 (email address login instead of computer user name/password).