I use them (that is, ‘Groups’, according to the IDE) for all kinds of things.
First off, each and every room in my house gets a separate ‘Group’ in the IDE.
Then, if the bedroom has a closet, that closet gets a ‘Group’. If it has a bathroom, that gets a ‘Group’.
In the kitchen, the pantry has its own ‘Group’. In the Theater Room, the Bar Area has its own ‘Group’. The Mud Room has its own 'Group, as do both the ‘Visitor Bathroom’ and the ‘Laundry Room’ which come off of it.
The main patio has one, and so do the main deck, the garden area, the driveway, the front sidewalk, the garage, the workshop, the stairway to the upper floor, the upper hallway, my office, her office, my closet, her closet, and on and on.
Beyond that, not everything that is a Smart Thing is something that is solely related to a ‘Room’ in a house.
e.g.1
I have 12 ‘Modes’ in my SmartThings system at my primary residence.
Well, in order to keep them in the proper on/off state, I have a corresponding set of simulated switches that mirror and interact with the Modes. I have webCoRE rules that monitor for various things, and which keep my system in the correct Mode, depending on time of day, etc.
Just in case you ask, “Why?”…
Well, if (somehow; accidental touching, glitches, forgetful testing, whatever) the system gets into a Mode other than the one that it really should be in, this set of rules and simulated switches quickly puts it back to the correct one. Oh…and yes…this was an issue for me once in a while at one time in the past. However, since I have had this system in place, my SmartThings system has always remained in the correct Mode.
In fact, I even sold my house in July of this year, put all of my HA stuff in storage, and didn’t take it out until this fall…in a completely different state, and in a different time zone, and BAM!, other than whatever HA items were left in the old house, everything worked perfectly, just as it had been working previously in the old house. 
Anyway…
This set of simulated switches needs to ‘live’ somewhere in my long list of devices, and so I created a ‘Group’ to hold them.
e.g.2
I have several other systems in place that work similarly, helping to keep all of my various status designations in place and working properly
(e.g. Presence,
Emergency Status,
HA Status,
Seasons,
Current Activity,
Services & Utilities,
among others. Each subset has its own set of simulated switches, which have their own ‘Group’.
e.g.3
I could go on, but I think you get the picture.
In order to group items which are related to each other in a way that makes sense for me, I use ‘Groups’ in the IDE.
As stated in my earlier post, even though my original list of ‘Groups’ needed went over the 100 mark, since it wasn’t very far over, I was able to find a few others in the mix that I could sacrifice in order to give more important ones a ‘Group’ of their own.
Eventually, it would be nice to be able to have every logical group that needs a ‘Group’ in the IDE have one, but for now, my workaround is fine. 
EDIT: @jody.albritton
I guess it wasn’t clear, but were you going to respond to my answer to your question?
I wasn’t expecting anything big, or complex, and I know you’re super busy and all, but I’m interested in hearing your thoughts at some point.