Damonjynx,
I am glad to hear you have already thought about the grid size and how it will fit with standard minis! That will make your project even more DM friendly. As I stated in the Flagstone thread, I think the space for doors rather than including them pre-planted is very wise, and will allow DMs to better control what they are building from the random tables. Furthermore, there are several minis for tables, chairs, chests, etc. and there is no need to include them in your set. When I have time I will have to look at your google docs to give you better feedback on that.
My only concern regarding this phase of your project is the assumption that all visible exits from the entry room are 10’ wide. I understand why it is you went with this, and my only counter is in regards to the possibility of rolling a door or pathway to the contrary. However, I find it to be a very small problem, as I prefer all major exits from the entry to be 10’, with storage rooms and secret passages as the only exception. Keep up the beautiful work!!