How should I setup hard drives for virtual machines?

Also, no there's no need to do a bunch of separate RAID 1s

No, never use RAID 5.

Otherwise almost anything is OK. The easiest config would probably be to create several RAID 1 arrays, and then use one of them for each OS.

Using Raid1 is the most inefficient usage of storage. There is nothing wrong with Raid5 and if you are worried about performance then go for Raid10.

Raid 1 is very efficient, particularly for VM's, as each VM has it's own array and you don't have more than one VM on the same array slowing things down. RAID 5 on the other hand is absolutely unreliable, hard to manage properly and slow, particularly if you run many VM's off it at the same time. RAID 5 was something that may have been OK decades ago, but today it is totally outdated and unreliable.

RAID1 is very inefficient for storage usage (ie you create a 60 GB drive the other 12 GB is notch usable for a data drive for another VM).  How do you know that requirement won't change and more VMs might be required.  If RAID5 is so bad then why is it still used by SAN manufacturers.  With the cache provided on array controllers, RAID5 is not an issue.  I am sure this individual is not going to be pushing the drives to its limits continuously.  Heck, if every array created is RAID1, not only are you wasting drives but not to mention increasing your electricity bill and Carbon footprint just to be able to say I have so much IO available where performance gains are negligible to end users.   PS most operations are read and RAID5 is goo for that.

I fail to see any reason why RAID 1 should use more electricity than RAID 5, and emit more Carbon dioxide. The asker has 16 disks, and those would use the same amount of electricity in any RAID configuration. Actually the RAID controller would probably use more power with RAID 5, as it has to do more work, while RAID 1 is a simple mirror where there is no calculation for striping or parity necessary. In RAID 5, if a disk breaks, you are at very high risk should other disks in the array have issues, while with RAID 1 than risk is very low. 72GB is much more than enough space for any normal OS. The data would be on separate arrays

One further big problem of RAID 5 is the human factor. It is very easy to do something wrong, for example when rebuilding an array, I've seen many things that failed because of that, while with RAID 1 it is much harder to do things wrong.

Obviously you are not seeing the bigger picture.  You always plan for capacity growth and my last comment about electricity, etc was general about arrays.  If most arrays by users are created using RAID1, then obviously more drives will be required.  My comment was that we should give answers which can be utilized in most cases.  

RAID1 can also be buggered up where I have seen incompetent users insert wrong size drives and then end up losing both drives.  This is my last post and for the record I have managed more than 1000 servers so far and only in 2 circumstances, RAID5 didn't cut but then again those were for high def videos.

If you are finding a solution specifically for Microsoft virtualization than instead of going with windows server 2012/R2 standard I would recommend to go with Datacenter edition because that's the correct solution for virtualization as you can only have 2 vm's on standard edition and Datacenter edition can host unlimited i.e. as per hardware capability.

While I was going to use Hyper-V, the answers here opened options up for me. After a good deal of research, the solution I went with was to use ESX1 from a USB flash drive and four RAID5 arrays. I used four separate arrays so that if one went down, it would reduce impact as other services would remain up (except where AD dependent).

Thank to all for their help assistance.