I've just received my Hubitat (moving over from Smartthings) and am glad to be here at what is clearly an active community!
I'm currently strategizing at how to most effectively approach a few things at the same time:
I currently have NO motion sensors inside or outside the house.
I would like to be able to track motion throughout each room of the house for automation purposes.
MIGHT want to track motion outdoors, but that would be more for security purposes, and since I already have outdoor cameras, this one's a "maybe".
I want to create some smart indoor lighting routines that follow "if someone's in the room AND the lux is below x, bring the lights up to x" type logic.
Every room of the house currently has Philips Hue (white and color) bulbs. They're paired to the Hue Hub, and I've successfully paired the Hue Hub to Hubitat.
So with that said, I started searching the forums and was maybe a little overwhelmed by the different approaches. I see a lot of talk about Hue motion sensors (both indoor and outdoor), but....thought it made most sense to just write up the end goal, where I'm currently at, and see if maybe I could get some guidance from those who certainly are further along the automation journey than I
In terms of devices, I’d recommend looking at the cheaper end of the market and experimenting with single-purpose sensors (ie non-multi sensor), as you can then flood your house with them to trigger delightful motion lighting rules.
When I set off on the same path as you, I started with motion sensors like Smartthings ($25?) and a multi-sensor nearer $50, until I discovered that Iris 3326Ls were both better (smaller and more sensitive) and cheaper ($6 each in lots of 10 on eBay, although those deals seem to have dried up).
For lux, I started with a Sensative Strips lux sensor for ~$50, due to mixed reviews on multisensors at half the price. But Sensative Strips is too slow and coarse-grained in its reporting to be delightful (only updates when the lux level doubles or halves) and too expensive to deploy in every room. Whereas the latest Xiaomi Mijia light sensors - which I discovered last month via these forums - are fantastic, cost only ~$10 each and respond quickly to small lux changes. I’d recommend putting lux sensors in every room where you’ll have motion lighting if you can afford them; an outdoor lux sensor is good for figuring out when to turn on the garden lights, but only an in-room sensor will know how bright or gloomy a specific room is based on sunshine, cloud cover, aspect, internal decor, blinds/curtains, etc.
CoCoHue is an excellent reliable app that also gives you your Hue scenes imported to Hubitat. It also can import groups for dimming up/down the group using Hue’s zigbee group messaging.
Hue motion sensors are available on Costco’s website (if you’re a member) for much cheaper than retail.
Lux can be difficult since it will change when you turn on a light, or a light is turned on by motion. I find that motion, combined with multiple modes throughout the day, gives me nearly the same effect. I would set up some routines and get used to the hub before jumping into lux.
You will need repeaters for all those motion sensors. Samsung outlets (2018 model) work the best for me. Iris and Sylvania are also good, but won’t repeat for as many devices, so you will need more of them.