I’ve had Smarthings for about 2 1/2 years now. I’ve accumulated a lot of smart devices. Everything’s from a Rachio, Sonos, motion sensors, door sensors, leak sensors, ring doorbell, hue lights, Lurton switches, osram garden lights and a nest thermostat and some cameras.
Am I nuts, or is this what most veterans have?
I’m up to 80 devices. A lot of Hue bulbs, smart light switches, a couple lamp modules, four sonos devices, slew of multi sensors, garage door, three zwave locks, four door sensors, , water sensors, logitech harmony, an Echo and three Dots, outdoor security camera, netatmo package with rain gauge and wind gauge, ring door bell, eight sleep mattress cover, tried some cheap chinese gas sensors and never got them powered up correctly, two water valve motors.
It’s not normal per se, but it’s easy to accumulate a lot of things if you have a passion for home automation. There are just as many people with a couple bulbs and maybe a lamp socket as those of us with a lot of different types of devices.
there are already quite a few threads that are similar to this. Other than looking through the projects category it might be worth a look at the “get started” quick browse list in the community – created wiki. You should find some of those threads interesting, things like “top 10 things to do with smartthings,” “what device should I get next?” Etc
As far as what people have, there’s a huge variety regardless of how long they’ve had the system because one of the strengths of SmartThings is that so many different devices can work with it. So people can really customize it to what they want for their own Home. 
But definitely look at the “top 10” thread it should have a lot of what you were asking.
Also take a look at the “impress your friends” list that has some really cool stuff like a secret bookcase room, a magic wand, etc. 
Alexa, Turn on Kitchen PC
Alexa, Turn off Bedroom PC
If
Den PC is on
And
Den Motion is inactive
Then
Using Den PC
Wait 1 Hour
Turn Off
I am surprised that ST doesn’t have a native turn on/off PC app. I did a tutorial on how to use ST to turn on/off a PC and how to use the PC as a presence sensor for HA purposes. Even went further with using a cool app here called Host Pinger to sync the Virtual Switches to the actual PC state so it doesn’t matter if the PC is turned on/off physically or through ST.
Moderate Installation: