Kegged the Spruce Porter tonight and took a quick sample drink from it. It's a little bit overly strong right now, but it'll mellow with time. That's 3/4 bottle of spruce essence in a 3 gallon batch. I'm going to try and bring it by the next meeting, but can't make any promises yet.
I used the other 1/4 of the spruce essence bottle experimenting with other (store-bought) beers. I've found that the spruce goes really well with a highly bitter IPA, though it sort of takes over the aroma and a lot of the hop flavor as well, but it's good, which surprised me a bit. Spruce goes well with any dark beer (porter & stout), as I expected. Another good combination is spruce and smoked beers, which I also wasn't expecting. Of course, all of that is my opinion, yours may vary.
So that adds three new beers to the list of things I want to brew:
Bourbon Spruce Porter (just spruce instead of vanilla)
Smokey Spruce Ale (nice smoke/spruce balance, might do one pale, one amber and one brown)
Spruce IPA (like I hinted above, highly bitter IPA, with no flavor/aroma additions, just spruce added)