Thanks Steve. I think DRS groups and rules is a great start to ensuring the larger vm's stay on the larger (cpu) hosts, but I'll still have to figure out what I'll do about over subscription.
In one example, I think I ended up with a 24 vCPU vm on a host with 24 logical processors, and the host also had 3 or 4 other small vm's when the large vm just stopped responding and the host CPU shot to like 170% until I migrated the vm on to it's own host. I would imagine even on a slightly larger 32 logical processor host, this could still happen if I let enough of these smaller vm's intermingle with the big ones.