If you do get cacti, be sure that you get ones that aren’t spiny. You don’t want them to get pricked! There should be several varieties of succulents available at your local nursery. Succulents are basically desert plants that generally have large, fat leaves and no/soft spines. Several varieties stay quite small. They are very nice for adding color, and give an “authentic” look.
For a substrate, I like to use slate tiles that have been broken to make interesting shapes (be sure to soften the sharp edges). You can stack them to cover the gaps from the first layer. It’s also possible to make hides by using clear silicone (let it dry at least 48 hr). It is more work then paper towels, and can weigh a lot depending on how much you put inside...but it looks great. I recently switched from paper towels to slate, and my geckos seem to love it. They’re exploring much more actively then they did on the towels.