I'm brewing a Barleywine soon and wanted to add something to the secondary to make it interesting. I was thinking of doing some bourbon soaked oak cubes, but was also thinking some fruit would be good as well. Any suggestions/help would be appreciated.
I would say you have 3 tones you could go with.
herbal: cardamom, nutmeg, allspice or star anise. this might be a nice little warm note over the hops.
fruity: orange or lemon zest, or stone fruit(cherries, apricots, etc)
or extra bitter: Wormwood if you are a masochist
taste your wort to what it needs for good balance. I have a hard time making high gravity beers because they have bad balance and taste like bananas and vanilla, but good luck to you!