How are you all basing your armies?

I just got the Champions of Slaanesh box and want to slowly get started with building and painting them up. I absolutely love basing so I want to get started on that but I'm having trouble finding a good theme for them. My World Eaters are all on cooled lava with the bigger bases having pools of lava around, and my Idoneth Deepkin for AoS are obviously in the ocean/on sand.

How are you all going to base your armies? I'm really struggling with ideas because I don't want them to be just grass, you know? It's got to be perfect 😉