Hey Max, Another consideration is how to distribute the worklaods on the luns themselves.
While you defintely want to be concerned about distributing the i/o load across the hosts, the i/o activity per lun may be just as critical to achieve best performance.
Think about how many luns you want, and also, if you need a vmdk bigger than 256 GB, to make the block size of the lun appropriate for the largest file size you anticipate. (1MB block size = 256 GB max file size, 2MB block = 512 GB block size,etc.).
I would first look at the absolute amount that each of these servers are generating in terms of the amount of i/o, (iops/s, MB/s) and then look at spreading a high i/o server with a few small i/o servers per lun, and then per host. You don't want to put all your "heavy hitters" on the same lun or the same host.
Your examples seem to likely to distribute the load fairly evenly without looking at any actual data. Spreading the file servers and the database servers seems to make the most sense.
Another consideration you probably have already thought about, is to distribute mission critical workloads across different servers so if one host has problems. people do not lose the ability to print and read their email, and some other critical app(dhcp,dc, etc), whatever is most important in your organization. Good luck!
