Reddit mentions of Honeywell YTH8320ZW1007/U Z-Wave Enabled Programmable Thermostat

It depends if you want to control everything from one place or don;t mind using a separate app for each thing. IF you want an all-in-one solution, the best bet is a Vera pro or VeraLite from MiCasaVerde. You don't have to re-invent the wheel as most of your wants will work right out of the box. What it doesn't natively do, it is almost guaranteed that someone has already done the modification and you can just grab their code.

For the lock I would go with a Yale or Schlage. Even Kwikset has zigbee and z-wave models. Honeywell makes a nice thermostat for cheap. There are several ways to integrate your doorbell as well.

Otherwise, Nest is great, Dropcam is awesome, There are a whole host of cool single-focus products out there.

SmartThings Version 3 Hub (I have the Version 2 Hub...you will have to look around for this one):
https://www.amazon.com/Samsung-SmartThings-Generation-GP-U999SJVLGDA-Automation/dp/B07FJGGWJL/ref=sr_1_1_sspa?ie=UTF8&qid=1540989501&sr=8-1-spons&keywords=smartthings+hub+2nd+generation&psc=1

GE Z-Wave Plus On/Off Light Switch:
https://www.amazon.com/GE-Repeater-Required-Works-SmartThings-14291/dp/B01M1AHC3R/ref=sr_1_3?ie=UTF8&qid=1540989582&sr=8-3&keywords=z-wave+switch

GE Z-Wave Plus Dimmer Switch:
https://www.amazon.com/GE-Repeater-Required-Works-SmartThings-14291/dp/B07361Y54Z/ref=sr_1_3?ie=UTF8&qid=1540989582&sr=8-3&keywords=z-wave%2Bswitch&th=1

GE Add On Switch (if you have a 3-way or 4-way switch):
https://www.amazon.com/GE-Bluetooth-Wireless-STANDALONE-12723/dp/B00RKJS8MQ/ref=sr_1_3?ie=UTF8&qid=1540989718&sr=8-3&keywords=z-wave+add+on+switch

ZigBee Motion Sensors:
https://www.amazon.com/gp/product/B07F8ZHBLS/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

ZigBee Door Sensors:
https://www.amazon.com/gp/product/B07F956F3B/ref=oh_aui_detailpage_o01_s00?ie=UTF8&th=1

ZigBee Leak Sensors:
https://www.amazon.com/gp/product/B07F951JDP/ref=oh_aui_detailpage_o01_s00?ie=UTF8&th=1

ZigBee Outlet Plug (you will need to replicate your ZigBee mesh, I use to motion activate lamps, turn lamps on/off at sunset/sunrise, etc.):
https://www.amazon.com/gp/product/B07F96JB63/ref=oh_aui_detailpage_o01_s00?ie=UTF8&th=1

Z-Wave Thermostat:
https://www.amazon.com/gp/product/B005EJ7YO2/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

ZigBee RGB Landscape RGB LED Strips:
https://www.amazon.com/gp/product/B00R1PB2ZY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

ZigBee RGB Lightbulbs:
https://www.amazon.com/gp/product/B073ZBYXKQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Z-Wave Deadbolt:
https://www.amazon.com/Kwikset-SmartCode-Electronic-SmartThings-featuring/dp/B004F1B24I/ref=sr_1_12?s=hi&ie=UTF8&qid=1540990126&sr=1-12&keywords=z-wave+lock

Z-Wave Garage Door Opener:
https://www.amazon.com/GoControl-Linear-GD00Z-4-Z-Wave-Controller/dp/B00M75TEIU/ref=sr_1_4?s=hi&ie=UTF8&qid=1540990160&sr=1-4&keywords=z-wave+garage+door+opener

Sonos One Speakers (Great music, and talking through SmartThings):
https://www.amazon.com/gp/product/B074XN1LH3/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Amazon Echo Show (for Voice Control...an Echo Dot will work just fine too):
https://www.amazon.com/All-new-Echo-Show-2nd-Gen/dp/B077SXWSRP/ref=sr_1_1?s=electronics&ie=UTF8&qid=1540990254&sr=1-1&keywords=echo+show

That's about all I can think of at the moment.

If you are going to do this, do it in stages. Z-Wave and ZigBee are mesh networks...meaning that the reliability of the network gets much better the more devices you have. Also, with these mesh networks:

• Battery operated devices DO NOT reinforce the mesh
  
• The only devices that reinforce the mesh are devices that are always powered from the mains
  
  I see so many people complaining about how the Z-Wave or ZigBee devices don't work, when they are relying on too many battery operated devices.
  
  For Z-Wave devices, choose Z-Wave Plus over Z-Wave...it's the newest standard, and has much better range.
  
  In the US, Z-Wave operates in the 900 MHz spectrum and ZigBee in the 2.4 GHz spectrum. Personally, I "prefer" Z-Wave devices as there is a lot of "junk" in the 2.4 GHz spectrum right now. However, the ZigBee devices are operating reliably as I have a strong mesh setup (with non-battery operated devices).
  
  Two great application for the Leak Sensors:
  
  
• Near your hot water heater (when they go, they always leak)
  
• Under your A/C drip pan (if you have central air)
  
  Great applications for door open/close sensors:
  
  
• Turn closet lights on/off when the door opens or closes
  
• Turn on entry and hallway lights when an entry door opens, but only when it's dark (30 minutes before sunset or after sunrise)...turn off 1 minute later
  
• Notify me when my gun safe is opened
  
  Great Application for Motion Sensors
  
  
• Turn on outside ceiling fans (but only if the temp is above 72 degrees)
  
• Turn on lamps while motion is active when it's dark
  
  The motion sensors I linked above are the new ones...the magnetically mount. What's cool is that the magnet is in the sensor, and it's strong enough to attach the sensor to a dry wall screw (no need to mount the adapter bracket).

I think the Honeywell Z-Wave thermostat would work. The thermostat is locked by default I think.

Also, since the thermostat has a temperature sensor in it, you can either program the Vera to switch it off if the Nest is on, or just allow it to come on if the temperature is too low like a normal thermostat.

the model I use for my steam system (which supports a multitude of common wiring types) is the Honeywell YTH8320ZW1007/U.

Available here for $135

Like you, I am trying to avoid cloud-based services at all cost. I want my house to continue to function even if the internet connection goes down for some reason.

I've also got central Heat/AC with a Gas furnace and I just picked up Honeywell's Zwave Thermostat. Its quite nice although does have some quirks when integrated with Home-Assistant. I don't know how it compares with other zwave thermostats but I'm happy with it. Scheduling can be done through home-assistant or at the thermostat directly. Currently, I'm using the built in scheduling on the thermostat but it seems like a schedule through home-assistant is the way to go due to one of the aforementioned quirks.

I haven't set up any remote sensors temperature, but it should be fairly straightforward to have Home-Assistant control the thermostat based on the temperature of individual rooms or on an average among all sensors.

I also found NMap presence detection to be spotty. Recently I configured Owntracks with private MQTT and haven't looked back. Its light-years ahead of the NMap detection.

I personally am not concerned with the multi-sensors as I am not very interested in temperature. I do use motion sensors heavily to trigger events in Home-Assistant. If you wanted both, i'd go with the multi-sensors.