Agreed, this is definitely an "it depends" type of answer. There are so many variables. Client device types and capabilities with regards to spatial streams and channel width for example, client density, the primary applications that will be in use, if you will require any voice and/or location tracking services, the room sizes, building construction, neighboring networks/companies, etc, etc. These will all be inputs into your AP placement, density, channel plan, etc.
If it's a typical mix of users, on a typical mix of client devices, running the typical mix of apps with typical EMIX characteristics, we can certainly provide some rules of thumb like an AP per room or 2500 square feet per AP along with how to best do your cell sizing, etc.
If it's a reasonably-sized enterprise deployment the answer is almost always do a formal site survey, especially if it's your first time doing an enterprise deployment, because it's also an excellent learning process. For more info on that see my reply in this thread https://community.meraki.com/t5/Wireless-LAN/Should-you-always-do-a-site-survey/m-p/13274
Hope that helps!