I don't recommend making every decision based on data, but on hot issues where there's disagreement, confusion, or more fear than usual, it's a big help. I love gathering the best data I can then finding ways to make it sing.
Amy Jo Kim was inspired by Bartle and created a Social Action Matrix. I find this is a great way to frame discussions about which features to prioritize, either based on business objectives or performance—whether to build into new areas or reinforce what's awesome.
I use this when faced with a lot of ambiguous input (in this example, rows of focus test observations, columns of testers ordered sorted by age or gender), and want to reshape it into clear patterns. Color makes it much easier to interpret.
This is based on Lippincott's ideas about improving customers' "joy of anticipating an experience and warmth of remembering it." Modern products have to inspire loyalty by going beyond concentrating exclusively on the core interaction.
I've used Yu-kai Chou's Octalysis both to help during Discovery, as a way of helping people understand their product more formally, and later as a way to gauge progress. Using it with internal surveys has stimulated discussions about where people agree and disagree too.