Just a couple of ideas for you to consider.........
Creating additional planes...
Fully defining sketches...
Using Offset Entities...
Using Convert Entities...
Template Set Ups...
I could go on and on but you've only got half an hour and I'm just not sure exactly how basic or technical you want to be.
Weldments and 3d sketching.
Take something simple and model it top-down, SSP style. Then model it with mates. Then make a change to each and show them how the one with the mates breaks much more easily.
If you're talking about very new users. In addition to the points suggested already, I would talk about the benefits of using sketch relations vs. using dimensions and how they affect file size and rebuild times in complex models.
Then talk about design intent:
- How do you want the final part oriented? If it's symmetrical, do you want one of the standard planes to act as a plane of symmetry? Do you want to model half and then mirror it at the end? Think of where the planes will end up in the final part and how someone would use them to mate this in an assembly.
- If you can put all of the cut-extrudes in one feature, should you? How does this affect future modification? Is it easy for others to know what you have done when they need to make the change?
- When should draft and fillets be added? (this is a bit more advanced but it's best to add them as late as possible in the feature tree)
I know there is a lot more but those are some basics. Take a look at HORROR Museum - Parts - Assemblies - Drawings - Show us the Worst Feature Tree for inspiration on what drives people crazy.
I believe people showing up in user group meeting already know the basic.
Show them something new and interesting.
Tip and trick you know that can save time, make thing easier, to avoid problems down stream.
To further Dave's suggestion of "template setups"...
What's the difference between templates and sheet formats? What gets saved with each? How should you decide what things go in a template vs. sheet format?
Using the Help menu.
Two things I have always had trouble with in SolidWorks are:
1. Adjusting Appearances for Cosmetic Mesh (or creating custom mesh appearances).
2. Creating a single camera and then controlling the camera actions in Animation timeline. (I can do it - but it always seems that I am doing way to much work for something that is simple in my other CAD).
I would plan based on the skill level of your audience.
(User Groups are going to be pretty savvy, so you could do some advanced techniques.)
If you wanted to have some fun with the very basics, you could think about showing some techniques to be efficient when creating sketches.
Create a sketch that is "semi-complex" (being sloppy here is good for demonstration purposes.)
Use "Auto dimension" to fully define the sketch (this should make a huge mess of dimensions.)
Ask them if this demonstrates good "design intent" and if it would be easy to make changes.
Do a screen grab to refer back to later.
Use a filter and delete all dimensions (you could use "show relations", but we'll make it easy and keep the relations from the sketch.)
Now go through and add relations
Finish with well thought out dimensions to fully define the sketch
Show the difference in the two sketches.
A lot of people don't realize that you can have a robust, fully defined sketch with only a few dimensions if you put some thought into your relations, use Global Variables, use equations, link dimensions, and so on.
Even some of the "more seasoned" users can get some good information out of something like this.
EDIT: Basically what Alex Burnett said!
Also, show them that there are a lot more commands than the standard that comes with the install.
"Out of sight, out of mind..."
Maybe show where they can find the other commands to add to their menus? (Tools/Customize)
The "Hole Wizard" and "Thread" commands seem to get a lot of attention these days. Especially with 3D printing.
The "Flex" command confuses a lot of users, sometimes myself.
As others have said, it's difficult to offer suggestions without knowing your audience, but you might consider showing how powerful custom properties can be.