I quite like the sound of a black ipa or an attempt at producing something that might pass as an English cask ale (despite being bottled).
I might be interested in a beer that uses foraged ingredients, I’ve brewed with rose petals, geranium leaves, lemon grass, and spruce - don’t use spruce unless you like the smell and taste of “pine-fresh” toilet cleaners!
I can’t see myself drinking a whole keg of anything like a barley wine so I probably don’t have any great interest in slow-burners unless it’s an Impy because I’ll brew one of those anyway. As an idea though, a lambic, bretted, or oaked ale might be an interesting challenge.