Its been out a while now but well worth mentioning that VMware have a fantastic tool to help you design your Horizon deployments.
Use the web-based tool and follow the workflow, identifying your use cases, workforce, service qualities, infrastructure, assessment data (options to import from Lakeside) and design decisions.
You are then presented with a profile result and a really useful Logical Architecture Diagram.
You can save multiple profiles and export them to PPT. There are also template workloads in the tool, for office worker, power users, etc, in case you are unsure of the IOPS and compute your users are generating. Always better to run some monitoring tools such as Lakeside or LWL Stratusphere to get local knowledge where possible.
My experience with using the tool is that it is super quick to get some really useful information and is largely accurate but mindful of the VM to CPU ratio, it can be quite conservative. Nevertheless a really excellent tool.