Ideal VLAN Configuration - Please Help! Every Networking Expert I Talk to Contradicts the One Before

I'm the defacto IT guy for a construction company and we are upgrading to a brand new office.

The owners gave me free reign to design the entire IT infrastructure for the new building. I researched everything exhaustively, designed the server room, bought all the equipment, picked out the subcontractors, everything. It's been fun for a geek like me.

But I've never messed with a network as complex as this one will be, and as a jack-of-all trades IT guy, networking is not my strongest area. Nevertheless I did my best and made up a network diagram of my plan.

I then crowdsourced it to the Spiceworks community asking for advice/critiques. In the past they've been a good resource for me, and indeed this time I got what appeared to be really good advice from networking experts. They critiqued my initial plans and convinced me that I was "over-VLANing". After many revisions they helped me evolve my network plans to this. From 7 VLANs to 4.

But the introduction of an L3 switch for inter-VLAN routing and changing the gateway to something other than the firewall were both fairly intimidating to me, so I hired a consultant to review my plans and assist with implementation if the need arose. He took one look at my plans and basically said "Wow.....ok..... that's not how I would do it but I'll implement it however you want." With a very "Your funeral." tone.

So I ask him how he would do it, and he tells me IP phones, management interfaces, printers, basically everything should get it's own VLAN.

*sigh*

So I hire a DIFFERENT consultant, from a different company, hoping he will either agree with the last guy, or agree with the Spiceworks community. Neither. He recommends a flat network with no VLANs for a company our size (about 40 office employees and a dozen remote).

*half sigh half sob*

I'm completely lost. I feel like a religious person that's lost their faith. I have no idea who to believe and I'm doubting everything I think I know.

I understand this stuff can be as much an art as a science, but REALLY?! Is there really no right or wrong way to do this? Why can't I find anything resembling a consensus from you networking gurus!?

Here is the latest revision of my network diagram. I'd really appreciate any input, because at this point I feel like I know less than when I started.