Good practices for animation control?

So I'm using Spriter for my animations, and that has allowed me to create a variety of animations for my character. However, as I add more moves and options, I'm finding that the page which controls the animations I'm playing is getting pretty unwieldy to work with. My current approach started out very simple (ie: If on ground + is moving then set animation to running), but those kind of condition-checks become increasingly large and ugly as the project gets bigger.

I'm not so much looking for specific code help as general ideas. I'd like to find an approach to controlling animations that lets me add new ones for specific events, without having to go back through a bunch of old events and changing conditions to make it all work. Has anyone found a good modular approach to controlling which animations play for complex characters? I'm thinking of doing a queue of some kind with priority levels (so a high-priority animation can override a low-priority one), but I'm looking for other ideas.

Thoughts? How have you handled complex animation controllers in the past?

Start off with a low number of conditions for the main animations, so running right = running anim, running left = running anim+mirrored, not running = idle. You are bound to come across logic that conflicts with other logic when playing certain anims, bugs are expected but they can be easily fixed if you keep the logic simple and not too convoluted. I'm not sure something like 'is on ground' is needed unless you're triggering different anims for different types of ground. If you're coming across any specific problems then detail them here and someone will help simplify the logic.