David,
I don't use cues/scenes/snippets a whole lot in my X32's, but when doing theatre stuff I tend to use snippets in my cues more than scenes. I think the X32 can save up to 100 scenes and 100 snippets, but up to 500 cues. There's third party software out there if you need to do more than that.
The way the X32 file structure is set up is different than any other mixer that I know of, but here's an overview. Scenes are a snapshot of the whole board, minus whatever you have "safed" (routing, etc). Snippets are a snapshot of a narrow portion or portions of the board. You can get very specific, such as recalling just the fader level of a particular channel, or FX mute, almost anything. Where I find this most useful for theatre stuff is to recall channel mutes and DCA assignments.
Cues are made up of a scene, a snippet, or both. I typically don't use scenes in a cue, just snippets. I use those snippets to change the channel mute status, DCA name, and DCA assignment of the channels I need in the cue. A DCA might be one person in one cue, a different person in the next cue, a group of people in the following cue, playback music for the next cue, and so on. DCA assignments change constantly throughout the show, and I set it up so the most important channels in the cue are on the first DCA's, the orchestra or playback is usually on the last. I don't have to touch the channel faders much, and the snippets take care of all the mutes and DCA assignments. It works really well.
I set up a snippet for every actor configuration in the show, and label them well. If a scene in the show has the exact same actors as a previous scene, I use the same snippet for both cues. If not, I make a new snippet. I typically use them just for mutes and DCA assignments, but you can easily have a snippet for almost anything (or lots of things at once, if you wanted).
You could use scenes for this, but it's a lot easier (in my opinion) to use snippets. With snippets you're not reloading the whole board every time you change a cue, you're just changing a few little things.
To add a scene or snippet to a cue, go to the home tab, scroll down to the cue you want to insert the scene/snippet onto, and select the scene or snippet you want to use in that cue. To make a snippet for mutes and DCA assignments you get the board set the way you want it, check the boxes for config and mute on the channels and DCA's you want to change, and save the snippet in an available slot.