Bridgman, that is a superbly unique space. I was going to recommend you look at what other attic users employed, but you are on terra incognita I think. Cool.
Brwsaw, you are in the 1% who finally know exactly how it feels (not sounds) when everything falls into place. When you can almost reach out and touch it or feel it moving while you stay put. Very cool and enviable story.
Mark, a good way to get started is to listen to "lively sounding" recordings with some reverb. A good one is Badfish by Sublime. There are so many cool things going on in the mix. From the beginning where you can feel like you are in the bar, or the siren swooping forward and around the room and then the huge and enveloping guitar solo. Another is Steven Page floating around in Brian Wilson.
When tracks not employing these obvious mixing/phasing tricks start to take shapes and forms in the room you are getting there. It can get uncanny.
