Model train figures - I like HO scale - you can find them at model train stores or online (I've bought them here, here, and here)
White thumbtacks, white paper towels (optional)
Small mirrors, trees, etc.
For large jars/vases, consider wadding up some paper towels to create a base that the Epson salt can sit on - it uses up less Epson salt and gives a fun landscape shape. For small jars/vases, you can just pour/spoon the Epson salt on its own - the spoon can be used to change the landscape a bit, although it will settle a lot more when you move it.
The glue dots can be used to stick the figures to mirrors (ice skating pond/rink), the bottom of the jar/vase, or (if you want more stability) to the top of a white thumbtack you can use to settle into the Epson salt. Depending on the scale of your figures, they may be just fine if you set them directly onto the Epson salt.
The possibilities are endless! See what you can come up with!! If you want to share pics of YOUR creations, just leave the link in the comments section.