Stomp Them Grapes is a good place, and probably closest to him. The biggest draw there is that it's around the corner from Crooked Stave!
Beer at Home is my lhbs, and they have locations in Englewood and Westminster... IMO, they have a better malt selection than Stomp them Grapes. They carry only White labs and dry yeast, while Stomp them Grapes carries mostly Wyeast, with a smattering of white labs and dried yeast.
The Brew Hut will be far away for him, but they have a great selection, and are attached to Dry Dock Brewery.
Hope that helps!