Empty carboy? My suggestion is to fill it. And soon.
You should brew an amber ale with guajillo and ancho peppers. I screwed up the carbonation on a batch that I did, but the flavors are awesome. I've used it for cooking, because I way over-carbed and it's a pain in the ass to pour into a glass.
Both of those types of peppers are pretty mild, in terms of heat, but pack a lot of flavor. So, don't be afraid to use a lot of them, it won't get overly spicy (as long as you leave the seeds out). I used about an ounce of each type in the last 15 minutes of the boil, and then another ounce of each in the fermenter. Just get the dried peppers and rehydrate them before adding them to the boil/fermenter. Oh yeah, I weighed them before rehydrating, so that was an ounce of dry peppers in each step.
If you are averse to amber ales, I think the flavors would actually work well with a dark Belgian style, either a dubbel (which I guess is essentially a Belgian amber ale) or a dark strong ale. A porter might work as well. But the bigger the beer, the more peppers you'd need to use to balance the flavors.