Distiller Todd Leopold (one of the two namesake 'Bros.') calls it 'the Mad Men effect'. In his words: "All of a sudden, cocktail culture for all of the 20-somethings became cool again." Denver's bar culture is heavily beer-based, and while brewpubs can be a lot fun, they rarely merit dressing up. Spirits feel fancier, and can be damn tasty too.
By booking a tour ahead of time, you'll have the opportunity to appreciate the entire process of crafting spirits. Leopold Bros. malt their own barley, mill their own grains, ferment their own mash, distill it all on site and never add artificial ingredients. The tools are displayed in immaculate German style, and of course samples are plentiful.
Definitely check the website, reserve ahead of time, and if you like the flavor of anise don't miss their absinthe!