I've never used RDS but have used VMWare a lot with those exact software packages. A few things I'll point out:
1) Reliability. How reliable is your network infrastructure out where folks are going to be using the software? At my last site, our network access was spotty at first then upgraded to where it was more reliable...but...the bandwidth wasn't great. I could get to files and such but it would NOT have supported the data flow needed for a remote desktop or virtual environment. At my current site, most of the facility does not have network access, so my laptop is basically an island when I'm on a machine.
2) Copies/Instances. Early on, I isolated FT View Studio from the other programs because of serious conflicts I encountered between RSLinx Enterprise (used by FTV) and RSLinx Classic (used by everything else). And, later, to support multiple versions of FT View Studio. And, later than that, to support a range of versions of RSLogix/Studio 5000 that did/didn't support a 64 bit OS. And different versions of Siemens software that didn't coexist well with each other or with AB.
3) Licensing. You seem to be coming from an IT background, but something to consider is connectivity between the license server and clients. At my last site, we were able to share a single license of an add-on language pack between multiple users by hosting it to a PC we could all ping. I tried that here and the firewall shut it down instantly. As an engineer in an organization that has very strict and centrally managed IT policies, I didn't pursue it because it wasn't really a need, but it's something to be aware of. Not only do your workstations need good, solid, reliable access to the VM/RDS systems, but you need to make sure that your FT Activation Manager instances can all communicate with each other without security issues. Also be aware of the number of VMs you'll need to create/license/maintain for the different software versions. If you're only using RSLogix 500 and the more recent versions of 5000 (say, after 24 or so), they can be on one 64 bit VM and the FT View studio on another (as long as you only need one version of FTV). Your licensing will need to support as many users as you have who all may need access to the PLC and HMI VMs at the same time.
4) Workstations. The workstations that your technicians/engineers will be using in the field will need to be connected to the servers as well as the machines. In my experience, these are generally (and should be) on different networks that aren't routable between each other except in very limited circumstances. The PCs will therefore need multiple NICs. The local user will need to be able to reconfigure at least one NIC to match the PLC's network without interfering with the connection to the VM/RDS.
My personal preference is to have a standalone workstation with the licenses, storage, and software that it needs. And the ability to make periodic backups of the VMs. I suppose I might think differently if I'd EVER had access to a good network that was fast and reliable throughout the facility, but I never have.